cmake: mingw also needs _FILE_OFFSET_BITS=64

CMakeLists.txt

@@ -170,7 +170,7 @@ endif()
 # On modern Unixes, this is typically already the case. The lone exception is
 # glibc, which may default to 32 bits. glibc allows this to be configured
 # by setting _FILE_OFFSET_BITS.
-if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR MINGW)
     add_definitions(-D_FILE_OFFSET_BITS=64)
 endif()