[clang] [clang][NFC] Factor out VLA checks in type traits (PR #88646)

[via cfe-commits]

================
@@ -5012,6 +5012,20 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
   return From;
 }
 
+/// Checks that type T is not a VLA.
+///
+/// @returns @c true if @p T is VLA and a diagnostic was emitted,
+/// @c false otherwise.
+static bool DiagnoseVLAInCXXTypeTrait(Sema &S, const TypeSourceInfo *T,
----------------
Sirraide wrote:

nit: do we need the `CXX` in the function name here?

https://github.com/llvm/llvm-project/pull/88646