Re-apply "Use standard CMake constructs to export the library's targets. (#260)"

Additionally, I have attempted to clean up some CMake issues to make the
package's build interface cleaner, in particular, avoiding polluting the
parent directory's include path with our config.h file (if PCRE2 is
being included as a subdirectory).

This re-adds changes from Theodore's commit
def175f, and partially reverts changes
from Carlo's commit 92d56a1.

---

Co-authored-by: Theodore Tsirpanis <teo@tsirpanis.gr>

Author: NWilson

.github/workflows/build.yml

@@ -121,6 +121,26 @@ jobs:
           ../maint/RunManifestTest install-dir ../maint/manifest-cmakeinstall-macos
           ../maint/RunSymbolTest install-dir/lib/ ../maint/
 
+      - name: Test CMake install interface
+        run: |
+          INSTALL_PREFIX=`pwd`/build/install-dir
+          cd maint/cmake-tests/install-interface
+          cmake -DCMAKE_PREFIX_PATH="$INSTALL_PREFIX" -B build
+          cd build
+          make
+          ./test_executable
+
+      - name: Test CMake build interface
+        run: |
+          BUILD_DIR=`pwd`
+          cp -rp maint/cmake-tests/build-interface ../cmake-tests-build-interface
+          cd ../cmake-tests-build-interface
+          ln -s "$BUILD_DIR" pcre2
+          cmake -B build
+          cd build
+          make
+          ./test_executable
+
   windows:
     name: Windows
     runs-on: windows-latest
@@ -150,6 +170,24 @@ jobs:
           ../maint/RunManifestTest.ps1 install-dir ../maint/manifest-cmakeinstall-windows
           ../maint/RunSymbolTest.ps1 install-dir/bin ../maint/
 
+      - name: Test CMake install interface
+        run: |
+          $INSTALL_PREFIX = (pwd).Path + "\build\install-dir"
+          cd maint/cmake-tests/install-interface
+          cmake -DCMAKE_PREFIX_PATH="$INSTALL_PREFIX" -B build -A ${{ matrix.arch }}
+          cmake --build build --config Release
+          ./build/Release/test_executable.exe
+
+      - name: Test CMake build interface
+        run: |
+          $BUILD_DIR = (pwd).Path
+          cp -Recurse -Path maint/cmake-tests/build-interface ../cmake-tests-build-interface
+          cd ../cmake-tests-build-interface
+          New-Item -ItemType SymbolicLink -Path "pcre2" -Target "$BUILD_DIR"
+          cmake -B build -A ${{ matrix.arch }}
+          cmake --build build --config Debug
+          ./build/Debug/test_executable.exe
+
   freebsd:
     name: FreeBSD
     runs-on: ubuntu-latest
@@ -191,7 +229,7 @@ jobs:
             echo "== CMake =="
             cd ../build-cmake
 
-            cmake -DPCRE2_SUPPORT_JIT=ON -DPCRE2_BUILD_PCRE2_16=ON -DPCRE2_BUILD_PCRE2_32=ON -DBUILD_SHARED_LIBS=ON -DBUILD_STATIC_LIBS=ON -DPCRE2_DEBUG=ON -DCMAKE_C_FLAGS="$CFLAGS_GCC_STYLE" -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -B build
+            cmake -DPCRE2_SUPPORT_JIT=ON -DPCRE2_BUILD_PCRE2_16=ON -DPCRE2_BUILD_PCRE2_32=ON -DBUILD_SHARED_LIBS=ON -DBUILD_STATIC_LIBS=ON -DPCRE2_DEBUG=ON -DCMAKE_C_FLAGS="$CFLAGS_GCC_STYLE" -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -DCMAKE_BUILD_TYPE=Release -B build
             cd build
             make -j3
             ctest -j3 --output-on-failure
@@ -273,7 +311,7 @@ jobs:
             echo "== CMake, 64-bit =="
             cd ../build-cmake-64
 
-            CC="cc -m64" cmake -DNCURSES_LIBRARY=termcap -DPCRE2_BUILD_PCRE2_16=ON -DPCRE2_BUILD_PCRE2_32=ON -DBUILD_SHARED_LIBS=ON -DBUILD_STATIC_LIBS=ON -DPCRE2_DEBUG=ON -DCMAKE_C_FLAGS="$CFLAGS_SOLARIS_CC" -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -B build
+            CC="cc -m64" cmake -DNCURSES_LIBRARY=termcap -DPCRE2_BUILD_PCRE2_16=ON -DPCRE2_BUILD_PCRE2_32=ON -DBUILD_SHARED_LIBS=ON -DBUILD_STATIC_LIBS=ON -DPCRE2_DEBUG=ON -DCMAKE_C_FLAGS="$CFLAGS_SOLARIS_CC" -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -DCMAKE_BUILD_TYPE=Release -B build
             cd build
             make
             ctest -j3 --output-on-failure

.github/workflows/dev.yml

@@ -200,6 +200,8 @@ jobs:
         run: |
           cd build
           cmake --install . --prefix install-dir
+          # Slight hack to trick RunManifestTest to pass with MinSizeRel.
+          mv install-dir/lib/cmake/pcre2/pcre2-targets-minsizerel.cmake install-dir/lib/cmake/pcre2/pcre2-targets-release.cmake
           ../maint/RunManifestTest install-dir ../maint/manifest-cmakeinstall-linux
           ../maint/RunSymbolTest install-dir/lib/ ../maint/