win32: use posix time on MinGW

Author: illwieckz

src/shared/platform/CMakeLists.txt

@@ -15,12 +15,17 @@ if (WIN32)
 		"win/nacl_semaphore.c"
 		"win/nacl_sync_win.cc"
 		"win/nacl_threads.c"
-		"win/nacl_time.c"
 		"win/nacl_timestamp.c"
 		"win/port_win.c"
 		"win/xlate_system_error.c"
 	)
 
+	if (MSVC)
+		list(APPEND PLATFORM_INPUTS "win/nacl_time.c")
+	else()
+		list(APPEND PLATFORM_INPUTS "posix/nacl_time.c")
+	endif()
+
 	if (MSVC)
 		list(APPEND PLATFORM_FLAGS "/D_CRT_RAND_S")
 		list(APPEND PLATFORM_FLAGS "/D_UNICODE")