[clang] [clang] move -Wcast-function-type under -Wextra (PR #77178)

[Vlad Serebrennikov via cfe-commits]

================
@@ -0,0 +1,42 @@
+// RUN: %clang_cc1 %s -fsyntax-only -Wextra -verify
----------------
Endilll wrote:

Yes, more `RUN` lines with different `-std=` options, and potentially more `expected` directives tailored for particular language mode. We have an example of this in C++ defect report tests: https://github.com/llvm/llvm-project/blob/main/clang/test/CXX/drs/dr6xx.cpp

Note that I might be biased here, as someone who've spent a significant time with C++ defect report test suite.

https://github.com/llvm/llvm-project/pull/77178