vpx_enc_fuzzer: limit number of encoded frames

Previously the encode loop was only bounded by the data size. With the
small resolutions being fuzzed this might result in hundreds of
thousands of frames to encode, resulting in a timeout. The frames are
now limited to 300.

Bug: 482163265, 482328006, 482494306, 482594458
Change-Id: I026de66933a267e1ce7e979005eea181bfd54a1e

Author: jzern

examples/vpx_enc_fuzzer.cc

@@ -80,6 +80,8 @@
 #define VPXC_INTERFACE(name) VPXC_INTERFACE_(name)
 #define VPXC_INTERFACE_(name) vpx_codec_##name##_cx()
 
+static constexpr int kMaxFrames = 300;
+
 extern "C" void usage_exit(void) { exit(EXIT_FAILURE); }
 
 static int vpx_img_plane_width(const vpx_image_t *img, int plane) {
@@ -230,7 +232,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
   size -= FUZZ_HDR_SZ;
 
   // Encode frames.
-  while (1) {
+  for (int i = 0; i < kMaxFrames; ++i) {
     int flags = 0;
     size_t size_read = fuzz_vpx_img_read(&raw, data, size);
     if (size_read == 0) break;