[libc] Add abort routine to replace old API.

abort routine will cause sig_xxx() reference.

components/libc/newlib/syscalls.c

@@ -447,3 +447,8 @@ void __libc_init_array(void)
 {
 	/* we not use __libc init_aray to initialize C++ objects */
 }
+
+void abort(void)
+{
+	return ;
+}