Fix KL43Z GCC_ARM build

libraries/mbed/targets/cmsis/TARGET_Freescale/TARGET_KLXX/TARGET_KL43Z/TOOLCHAIN_GCC_ARM/sys.cpp

@@ -1,32 +0,0 @@
-/* mbed Microcontroller Library - stackheap
- * Copyright (C) 2009-2011 ARM Limited. All rights reserved.
- *
- * Setup a fixed single stack/heap memory model,
- *  between the top of the RW/ZI region and the stackpointer
- */
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include <sys/types.h>
-#include <errno.h>
-
-extern void exit(int return_code);
-
-int _kill(int pid, int sig) {
-    errno = EINVAL;
-    return -1;
-}
-
-void _exit(int status) {
-  exit(status);
-}
-
-int _getpid(void) {
-  return 1;
-}
-
-#ifdef __cplusplus
-}
-#endif