Add a CMAKE_TOOLCHAIN_FILE to compile with MinGW

This is inspired by this blog post by Sylvain Beucler:
http://blog.beuc.net/posts/Cross-compiling_with_CMake/

diff --git a/cmake_modules/mingw_cross_toolchain.cmake b/cmake_modules/mingw_cross_toolchain.cmake
new file mode 100644 (file)
index 0000000..32ef5ab
--- /dev/null
+++ b/cmake_modules/mingw_cross_toolchain.cmake
@@ -0,0 +1,9 @@
+SET(CMAKE_SYSTEM_NAME Windows)
+include(CMakeForceCompiler)
+IF("${GNU_HOST}" STREQUAL "")
+    SET(GNU_HOST i586-mingw32msvc)
+ENDIF()
+# Prefix detection only works with compiler id "GNU"
+CMAKE_FORCE_C_COMPILER(${GNU_HOST}-gcc GNU)
+# CMake doesn't automatically look for prefixed 'windres', do it manually:
+SET(CMAKE_RC_COMPILER ${GNU_HOST}-windres)