protobuf: Fix a null/bool conversion.

BUG=none
TEST=none
TBR=agl

Review URL: https://chromiumcodereview.appspot.com/10386158

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137666 0039d316-1c4b-4281-b951-d872f2087c98

third_party/protobuf/src/google/protobuf/io/coded_stream.cc

@@ -452,7 +452,7 @@ bool CodedInputStream::ReadVarint64Fallback(uint64* value) {
 
     // We have overrun the maximum size of a varint (10 bytes).  The data
     // must be corrupt.
-    return NULL;
+    return false;
 
    done:
     Advance(ptr - buffer_);