minor cleanup of MinGW-related scripts

.github/workflows/build.yml

@@ -37,8 +37,10 @@ jobs:
         run: |
           ccache --zero-stats
           source /opt/qt5*/bin/qt5*-env.sh || true
-          mkdir build && cd build
-          cmake .. $CMAKE_OPTS -DCMAKE_INSTALL_PREFIX=./install
+          cmake -S . \
+                -B build \
+                -DCMAKE_INSTALL_PREFIX=./install \
+                $CMAKE_OPTS
       - name: Build
         run: cmake --build build
       - name: Run tests
@@ -194,8 +196,11 @@ jobs:
       - name: Configure
         run: |
           ccache --zero-stats
-          mkdir build && cd build
-          ../cmake/build_win${{ matrix.arch }}.sh
+          cmake -S . \
+                -B build \
+                -DCMAKE_INSTALL_PREFIX=./install \
+                -DCMAKE_TOOLCHAIN_FILE="./cmake/toolchains/MinGW-W64-${{ matrix.arch }}.cmake" \
+                $CMAKE_OPTS
       - name: Build
         run: cmake --build build
       - name: Package

cmake/toolchains/MinGW-W64-32.cmake

@@ -0,0 +1,6 @@
+
+set(WIN64                    FALSE)
+
+set(CMAKE_SYSTEM_PROCESSOR   i686)
+
+include(${CMAKE_CURRENT_LIST_DIR}/common/MinGW-W64.cmake)

cmake/toolchains/MinGW-W64-64.cmake

@@ -0,0 +1,9 @@
+
+set(WIN64                           TRUE)
+
+set(CMAKE_SYSTEM_PROCESSOR          x86_64)
+set(CMAKE_SYSTEM_PROCESSOR32        i686)
+
+set(CMAKE_TOOLCHAIN_FILE_32			"${CMAKE_CURRENT_LIST_DIR}/MinGW-W64-32.cmake")
+
+include(${CMAKE_CURRENT_LIST_DIR}/common/MinGW-W64.cmake)

cmake/toolchains/common/MinGW-W64.cmake

@@ -0,0 +1,24 @@
+# Toolchain for MinGW compiler
+
+set(CMAKE_SYSTEM_NAME               Windows)
+set(CMAKE_SYSTEM_VERSION            1)
+
+set(TOOLCHAIN_PREFIX      ${CMAKE_SYSTEM_PROCESSOR}-w64-mingw32)
+set(CMAKE_C_COMPILER      ${TOOLCHAIN_PREFIX}-gcc)
+set(CMAKE_CXX_COMPILER    ${TOOLCHAIN_PREFIX}-g++)
+set(CMAKE_RC_COMPILER     ${TOOLCHAIN_PREFIX}-windres)
+
+set(CMAKE_FIND_ROOT_PATH  /usr/${TOOLCHAIN_PREFIX})
+set(ENV{PKG_CONFIG}       /usr/bin/${TOOLCHAIN_PREFIX}-pkg-config)
+
+if(WIN64)
+	set(TOOLCHAIN_PREFIX32   ${CMAKE_SYSTEM_PROCESSOR32}-w64-mingw32)
+	set(CMAKE_C_COMPILER32   ${TOOLCHAIN_PREFIX32}-gcc)
+	set(CMAKE_CXX_COMPILER32 ${TOOLCHAIN_PREFIX32}-g++)
+endif()
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+# Search for libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)