Make mongoose more bare-metal Keil friendly. Declare settings after arch. Introduce MG_ENABLE_FILE

src/log.c

@@ -4,7 +4,9 @@
 #if MG_ENABLE_LOG
 static void mg_log_stdout(const void *buf, size_t len, void *userdata) {
   (void) userdata;
+#if MG_ENABLE_FILE
   fwrite(buf, 1, len, stdout);
+#endif
 }
 
 static const char *s_spec = "2";