Let CMAKE use the compilers already defined

patches/toolchain-linux-mingw.oglft.cmake

@@ -2,8 +2,8 @@
 SET(CMAKE_SYSTEM_NAME Windows)
 
 # which compilers to use for C and C++
-SET(CMAKE_C_COMPILER   i586-pc-mingw32-gcc)
-SET(CMAKE_CXX_COMPILER i586-pc-mingw32-g++)
+SET(CMAKE_C_COMPILER ${CC})
+SET(CMAKE_CXX_COMPILER ${CXX})
 
 # here is the target environment located
 SET(CMAKE_FIND_ROOT_PATH  ${OGLFT_INSTALL})