Add circleci mingw builder

.circleci/config.yml

@@ -478,6 +478,25 @@ jobs:
       - copy_rpm_artifacts:
           build: fedora-31
 
+  build_mingw:
+    docker:
+      - image: eu.gcr.io/clementine-data/mingw-w64:latest
+    environment:
+      PKG_CONFIG_PATH: /target/lib/pkgconfig
+    steps:
+      - checkout
+      - run:
+          name: CMake
+          working_directory: bin
+          command: >
+            cmake ..
+            -DCMAKE_TOOLCHAIN_FILE=../Toolchain-mingw32.cmake
+            -DCMAKE_BUILD_TYPE=Release
+      - run:
+          name: Make
+          working_directory: bin
+          command: make -j2
+
   build_mac:
     macos:
       xcode: "11.0.0"

Toolchain-mingw32.cmake

@@ -0,0 +1,17 @@
+# the name of the target operating system
+SET(CMAKE_SYSTEM_NAME Windows)
+
+# which compilers to use for C and C++
+SET(CMAKE_C_COMPILER i686-w64-mingw32-gcc)
+SET(CMAKE_CXX_COMPILER i686-w64-mingw32-g++)
+SET(CMAKE_RC_COMPILER i686-w64-mingw32-windres)
+
+# here is the target environment located
+SET(CMAKE_FIND_ROOT_PATH  /target )
+
+# adjust the default behaviour of the FIND_XXX() commands:
+# search headers and libraries in the target environment, search 
+# programs in the host environment
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)