[wasm] Fix -Wsign-compare warnings.

test/fuzzer/fuzzer.cc

Index: test/fuzzer/fuzzer.cc
diff --git a/test/fuzzer/fuzzer.cc b/test/fuzzer/fuzzer.cc
index 71a26b86b379eb428a63ae1063b9b352edf5c01f..cb4a287d7008c7bb3542a9ffad1009d41dd23cb8 100644
--- a/test/fuzzer/fuzzer.cc
+++ b/test/fuzzer/fuzzer.cc
@@ -42,7 +42,7 @@ int main(int argc, char* argv[]) {
   size_t bytes_read = fread(data, 1, size, input);
   fclose(input);
 
-  if (bytes_read != size) {
+  if (bytes_read != static_cast<size_t>(size)) {
     free(data);
     fprintf(stderr, "Failed to read %s\n", argv[1]);
     return 1;