standalone: uprev to clang-19

Follow recent chromium rolls.

Change-Id: Id6221a6aeef00dd5b3c6a1ba56ce788bb03ce4f5
diff --git a/gn/standalone/BUILD.gn b/gn/standalone/BUILD.gn
index 98cb01e..ecd5c95 100644
--- a/gn/standalone/BUILD.gn
+++ b/gn/standalone/BUILD.gn
@@ -83,6 +83,7 @@
       "-Wno-gnu-zero-variadic-macro-arguments",
       "-Wno-padded",
       "-Wno-poison-system-directories",
+      "-Wno-pre-c11-compat",
       "-Wno-reserved-id-macro",
       "-Wno-reserved-identifier",
       "-Wno-shadow-uncaptured-local",