Fix #1285 - __builtin___snprintf_chk warning. Tighten test flags and refactor the code to squash all warnings

test/mongoose_custom.h

@@ -0,0 +1,22 @@
+// Required by the test ARM build
+#pragma once
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+int clock_gettime(clockid_t clock_id, struct timespec *tp);
+
+#define MG_DIRSEP '/'
+#define MG_INT64_FMT "%lld"
+#define MG_PATH_MAX 100
+#define MG_ENABLE_SOCKET 0
+