Prevent nanopb fuzzers from spamming logs

test/core/nanopb/fuzzer_response.c

@@ -41,7 +41,10 @@
 bool squelch = true;
 bool leak_check = true;
 
+static void dont_log(gpr_log_func_args *args) {}
+
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  if (squelch) gpr_set_log_function(dont_log);
   gpr_slice slice = gpr_slice_from_copied_buffer((const char *)data, size);
   grpc_grpclb_initial_response *response;
   if ((response = grpc_grpclb_initial_response_parse(slice))) {

test/core/nanopb/fuzzer_serverlist.c

@@ -41,7 +41,10 @@
 bool squelch = true;
 bool leak_check = true;
 
+static void dont_log(gpr_log_func_args *args) {}
+
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  if (squelch) gpr_set_log_function(dont_log);
   gpr_slice slice = gpr_slice_from_copied_buffer((const char *)data, size);
   grpc_grpclb_serverlist *serverlist;
   if ((serverlist = grpc_grpclb_response_parse_serverlist(slice))) {