doc: Use CONFIG_SITE instead of --prefix

Author: hebasto

depends/README.md

@@ -12,15 +12,18 @@ For example:
 
     make HOST=x86_64-w64-mingw32 -j4
 
-**Bitcoin Core's configure script by default will ignore the depends output.** In
+**Bitcoin Core's `configure` script by default will ignore the depends output.** In
 order for it to pick up libraries, tools, and settings from the depends build,
-you must point it at the appropriate `--prefix` directory generated by the
-build. In the above example, a prefix dir named x86_64-w64-mingw32 will be
-created. To use it for Bitcoin:
+you must set the `CONFIG_SITE` environment variable to point to a `config.site` settings file.
+In the above example, a file named `depends/x86_64-w64-mingw32/share/config.site` will be
+created. To use it during compilation:
 
-    ./configure --prefix=$PWD/depends/x86_64-w64-mingw32
+    CONFIG_SITE=$PWD/depends/x86_64-w64-mingw32/share/config.site ./configure
 
-Common `host-platform-triplets` for cross compilation are:
+The default install prefix when using `config.site` is `--prefix=depends/<host-platform-triplet>`,
+so depends build outputs will be installed in that location.
+
+Common `host-platform-triplet`s for cross compilation are:
 
 - `i686-pc-linux-gnu` for Linux 32 bit
 - `x86_64-pc-linux-gnu` for x86 Linux
@@ -133,4 +136,3 @@ This is an example command for a default build with no disabled dependencies:
 
 - [description.md](description.md): General description of the depends system
 - [packages.md](packages.md): Steps for adding packages
-

doc/build-unix.md

@@ -331,7 +331,7 @@ To build executables for ARM:
     make HOST=arm-linux-gnueabihf NO_QT=1
     cd ..
     ./autogen.sh
-    ./configure --prefix=$PWD/depends/arm-linux-gnueabihf --enable-glibc-back-compat --enable-reduce-exports LDFLAGS=-static-libstdc++
+    CONFIG_SITE=$PWD/depends/arm-linux-gnueabihf/share/config.site ./configure --enable-glibc-back-compat --enable-reduce-exports LDFLAGS=-static-libstdc++
     make
 
 

doc/multiprocess.md

@@ -24,7 +24,7 @@ The multiprocess feature requires [Cap'n Proto](https://capnproto.org/) and [lib
 ```
 cd <BITCOIN_SOURCE_DIRECTORY>
 make -C depends NO_QT=1 MULTIPROCESS=1
-./configure --prefix=$PWD/depends/x86_64-pc-linux-gnu
+CONFIG_SITE=$PWD/depends/x86_64-pc-linux-gnu/share/config.site ./configure
 make
 src/bitcoin-node -regtest -printtoconsole -debug=ipc
 BITCOIND=bitcoin-node test/functional/test_runner.py