GCC4.9.2/bin/../lib/gcc/x86_64-w64-mingw32/4.9.2/../../../../x86_64-w64-mingw32/lib/../lib\libmingw32.a(lib64_libmingw32_a-crt0_c.o):crt0_c.c:(.text.startup+0x25): undefined reference to `WinMain' collect2.exe: error: ld returned 1 exit status