Use int debug level

test/fuzz.c

@@ -7,7 +7,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *, size_t);
 #endif
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
-  mg_log_set("0");
+  mg_log_set(MG_LL_NONE);
 
   struct mg_dns_message dm;
   mg_dns_parse(data, size, &dm);

test/unit_test.c

@@ -2483,7 +2483,7 @@ static void test_rpc(void) {
 int main(void) {
   const char *debug_level = getenv("V");
   if (debug_level == NULL) debug_level = "3";
-  mg_log_set(debug_level);
+  mg_log_set(atoi(debug_level));
 
   test_json();
   test_rpc();