ci: remove submodule builds (#3246)

Submodules are difficult to support, and probably not a best practice,
as the target names must remain different from all the targets that the
user might define (CMake has a global namespace for targets).

Author: coryan

README.md

@@ -489,27 +489,26 @@ ctest --output-on-failure
 You will find compiled binaries in `cmake-out\` respective to their
 source directories.
 
-### Install
-
-By default `google-cloud-cpp` downloads and compiles all its dependencies.
-The default configuration disables the `install` target, because the version of
-the dependencies downloaded by `google-cloud-cpp` may conflict with the versions
-already installed in your system, or with the versions you want to use for
-development.
-
-To install `google-cloud-cpp` you must first install all its dependencies. Then
-you must configure `google-cloud-cpp` to find these dependencies, and install
-it.
-
-Installing the dependencies themselves may be as simple as using the package
-manager for your platform, or may require manually downloading, compiling, and
-installing said dependencies.  The [INSTALL.md](INSTALL.md) file describes how
-to successfully install `google-cloud-cpp` on several platforms.
-
-Alternatively, if you prefer to use `google-cloud-cpp` as a submodule, you can
-use the CMake command
-[`add_subdirectory()`](https://cmake.org/cmake/help/latest/command/add_subdirectory.html)
-to include `google-cloud-cpp` directly in your CMake project.
+### Installing `google-cloud-cpp` using CMake
+
+The default CMake builds for `google-cloud-cpp` assume that all the necessary
+dependencies are installed in your system. Installing the dependencies may be as
+simple as using the package manager for your platform, or may require manually
+downloading, compiling, and installing a number of additional libraries. The
+[INSTALL.md](INSTALL.md) file describes how to successfully install
+`google-cloud-cpp` on several platforms.
+
+If installing all the dependencies is not an option for you, consider using a
+CMake [super build][super-build-link], an example of such can be found in the
+`super/` directory.
+
+Alternatively, you may be able to use `google-cloud-cpp` as a git submodule of
+your source, and then use CMake's [`add_subdirectory()`][add-subdirectory-link]
+command to compile the project as part of your build. However, this is **not**
+a configuration that we test routinely and/or we recommend for teams working on
+large projects.
+
+[add-subdirectory-link]: https://cmake.org/cmake/help/latest/command/add_subdirectory.html
 
 ## Versioning
 

ci/kokoro/install/Dockerfile.centos-7

@@ -206,9 +206,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.debian-buster

@@ -169,9 +169,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.debian-stretch

@@ -179,9 +179,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.fedora

@@ -147,9 +147,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.opensuse-leap

@@ -220,9 +220,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.opensuse-tumbleweed

@@ -142,9 +142,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.ubuntu-bionic

@@ -172,9 +172,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.ubuntu-trusty

@@ -242,9 +242,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN cmake -H. -B/i/storage -DCMAKE_FIND_ROOT_PATH="/usr/local/curl;/usr/local/ssl"
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out -DCMAKE_FIND_ROOT_PATH="/usr/local/curl;/usr/local/ssl"
-RUN cmake --build cmake-out -- -j ${NCPU:-4}

ci/kokoro/install/Dockerfile.ubuntu-xenial

@@ -195,9 +195,3 @@ WORKDIR /home/build/test-install-cmake-storage
 COPY ci/test-install/storage /home/build/test-install-cmake-storage
 RUN env -u PKG_CONFIG_PATH cmake -H. -B/i/storage
 RUN cmake --build /i/storage -- -j ${NCPU:-4}
-
-WORKDIR /home/build/test-submodule
-COPY ci/test-install /home/build/test-submodule
-COPY . /home/build/test-submodule/submodule/google-cloud-cpp
-RUN cmake -Hsubmodule -Bcmake-out
-RUN cmake --build cmake-out -- -j ${NCPU:-4}