Compile fuzzer sources in standalone builds. (try 2)

testing/libfuzzer/xfa_codec_fuzzer.h

Index: testing/libfuzzer/xfa_codec_fuzzer.h
diff --git a/testing/libfuzzer/xfa_codec_fuzzer.h b/testing/libfuzzer/xfa_codec_fuzzer.h
index bf8f985f34dafa06faf4a09907db9bba702949c5..4281db0ac90b4b6ccc05e055ac0ec2be49c2878a 100644
--- a/testing/libfuzzer/xfa_codec_fuzzer.h
+++ b/testing/libfuzzer/xfa_codec_fuzzer.h
@@ -49,7 +49,7 @@ class XFACodecFuzzer {
     void Release() override {}
 
     bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override {
-      if (offset < 0 || offset >= m_size)
+      if (offset < 0 || static_cast<size_t>(offset) >= m_size)
         return false;
       if (offset + size > m_size)
         size = m_size - offset;