Merge bitcoin/bitcoin#24392: build: Fix configuring depends with cmake

ff4a38a build: Fix configuring depends with cmake (Hennadii Stepanov)

Pull request description:

  This PR fixes bitcoin/bitcoin#24389.

  On master (28aa0e3) configuring of the `libmultiprocess` package for the `x86_64-w64-mingw32` target fails:
  ```
  $ cd depends
  $ make libmultiprocess_configured MULTIPROCESS=1 HOST=x86_64-w64-mingw32
  Configuring libmultiprocess...
  CMake Warning:
    No source or binary directory provided.  Both will be assumed to be the
    same as the current working directory, but note that this warning will
    become a fatal error in future CMake releases.

  -- The CXX compiler identification is GNU 9.3.0
  -- Check for working CXX compiler: /usr/bin/x86_64-w64-mingw32-g++-posix
  -- Check for working CXX compiler: /usr/bin/x86_64-w64-mingw32-g++-posix -- broken
  CMake Error at /usr/share/cmake-3.16/Modules/CMakeTestCXXCompiler.cmake:53 (message):
    The C++ compiler

      "/usr/bin/x86_64-w64-mingw32-g++-posix"

    is not able to compile a simple test program.

    It fails with the following output:

      Change Dir: /home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeTmp

      Run Build Command(s):/usr/bin/make cmTC_93273/fast && make[1]: Entering directory '/home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeTmp'
      /usr/bin/make -f CMakeFiles/cmTC_93273.dir/build.make CMakeFiles/cmTC_93273.dir/build
      make[2]: Entering directory '/home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeTmp'
      Building CXX object CMakeFiles/cmTC_93273.dir/testCXXCompiler.cxx.o
      /usr/bin/x86_64-w64-mingw32-g++-posix    -I/home/hebasto/GitHub/bitcoin/depends/x86_64-w64-mingw32/include     -pipe -O2    -o CMakeFiles/cmTC_93273.dir/testCXXCompiler.cxx.o -c /home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeTmp/testCXXCompiler.cxx
      Linking CXX executable cmTC_93273
      /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_93273.dir/link.txt --verbose=1
      /usr/bin/x86_64-w64-mingw32-g++-posix  -I/home/hebasto/GitHub/bitcoin/depends/x86_64-w64-mingw32/include     -pipe -O2   -L/home/hebasto/GitHub/bitcoin/depends/x86_64-w64-mingw32/lib  -rdynamic CMakeFiles/cmTC_93273.dir/testCXXCompiler.cxx.o  -o cmTC_93273
      x86_64-w64-mingw32-g++-posix: error: unrecognized command line option ‘-rdynamic’
      make[2]: *** [CMakeFiles/cmTC_93273.dir/build.make:87: cmTC_93273] Error 1
      make[2]: Leaving directory '/home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeTmp'
      make[1]: *** [Makefile:121: cmTC_93273/fast] Error 2
      make[1]: Leaving directory '/home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeTmp'

    CMake will not be able to correctly generate this project.
  Call Stack (most recent call first):
    CMakeLists.txt:6 (project)

  -- Configuring incomplete, errors occurred!
  See also "/home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeOutput.log".
  See also "/home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/CMakeFiles/CMakeError.log".
  make: *** [funcs.mk:283: /home/hebasto/GitHub/bitcoin/depends/work/build/x86_64-w64-mingw32/libmultiprocess/d576d975debdc9090bd2582f83f49c76c0061698-f496b1e64cb/./.stamp_configured] Error 1

  ```

  The reason of that failure is the unset `-DCMAKE_SYSTEM_NAME` flag:
  ```
  $ make print-libmultiprocess_cmake MULTIPROCESS=1 HOST=x86_64-w64-mingw32
  libmultiprocess_cmake=env CC="x86_64-w64-mingw32-gcc" CFLAGS="  -I/home/hebasto/GitHub/bitcoin/depends/x86_64-w64-mingw32/include     -pipe -O2    " CXX="x86_64-w64-mingw32-g++-posix" CXXFLAGS="  -I/home/hebasto/GitHub/bitcoin/depends/x86_64-w64-mingw32/include     -pipe -O2    " LDFLAGS="  -L/home/hebasto/GitHub/bitcoin/depends/x86_64-w64-mingw32/lib    " cmake -DCMAKE_INSTALL_PREFIX:PATH="/home/hebasto/GitHub/bitcoin/depends/x86_64-w64-mingw32" -DCMAKE_SYSTEM_NAME= -DCMAKE_C_COMPILER_TARGET=x86_64-w64-mingw32 -DCMAKE_CXX_COMPILER_TARGET=x86_64-w64-mingw32
  ```

  This PR fixes this error:
  ```
  $ make libmultiprocess_configured MULTIPROCESS=1 HOST=x86_64-w64-mingw32
  $ # no errors
  ```

ACKs for top commit:
  fanquake:
    ACK ff4a38a - going to merge this now, and we can follow up with more cmake improvements.

Tree-SHA512: bd8d8b2f4eedcc8c46cf995b9c39493ea4d0b13c224f77ef62985304ebd392f05119043a06f1401c64f962007a8faa4bb53715d99a408ee6c33bb49a2dd650ba

Author: fanquake

depends/hosts/mingw32.mk

@@ -13,4 +13,4 @@ mingw32_debug_CXXFLAGS=$(mingw32_debug_CFLAGS)
 
 mingw32_debug_CPPFLAGS=-D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC
 
-mingw_cmake_system=Windows
+mingw32_cmake_system=Windows