remove Http2Codec::parseExHeaders decl

Summary: Cleanup diff -- Http2Codec::parseExHeaders was removed a while back but I forgot to remove this method declaration in Http2Codec

Reviewed By: SUJP123

Differential Revision: D121072294

fbshipit-source-id: 78669b3663602985423edd92d819027637aec196

Author: hanidamlaj

proxygen/lib/http/codec/HTTP2Codec.h

@@ -197,7 +197,6 @@ class HTTP2Codec
                                size_t bufLen,
                                size_t& parsed);
   ErrorCode parseHeaders(folly::io::Cursor& cursor);
-  ErrorCode parseExHeaders(folly::io::Cursor& cursor);
   ErrorCode parseRFC9218Priority(folly::io::Cursor& cursor);
   ErrorCode parseRstStream(folly::io::Cursor& cursor);
   ErrorCode parseSettings(folly::io::Cursor& cursor);