Add more warnings to QUIC

This increases the robustness of the codebase and simplifies QUICHE merges.

gfe-relnote: n/a, only adds compilation warning
PiperOrigin-RevId: 253919509
Change-Id: I396139fa3d6bc5876a879fa479f33a0ff1b68614

quic/core/qpack/qpack_constants.cc

diff --git a/quic/core/qpack/qpack_constants.cc b/quic/core/qpack/qpack_constants.cc
index dd4487d..6644918 100644
--- a/quic/core/qpack/qpack_constants.cc
+++ b/quic/core/qpack/qpack_constants.cc
@@ -30,6 +30,8 @@
     }
     DCHECK_EQ(1u, match_count) << static_cast<int>(byte);
   }
+#else
+  (void)language;
 #endif
 }