add mingw dependencies/include to include path

Older versions of mingw64 do not have the versionhelpers.h header, add
it to the dependencies submodule include/ directory and add it to
include_directories() for mingw in cmake.

CMakeLists.txt

@@ -344,6 +344,7 @@ if(WIN32)
     endif()
 
     if(MINGW)
+        include_directories("${CMAKE_SOURCE_DIR}/dependencies/include")
         include_directories("${CMAKE_SOURCE_DIR}/dependencies/mingw-xaudio/include")
     elseif(MSVC)
         set(DEPS_MSVC "${CMAKE_SOURCE_DIR}/dependencies/msvc")