[clang] [clang] Catch missing format attributes (PR #70024)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-win` running on `sie-win-worker` while building `clang` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/46/builds/1528

Here is the relevant piece of the build log for the reference:
```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'Clang :: Sema/attr-format-missing.c' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
z:\b\llvm-clang-x86_64-sie-win\build\bin\clang.exe -cc1 -internal-isystem Z:\b\llvm-clang-x86_64-sie-win\build\lib\clang\19\include -nostdsysteminc -fsyntax-only -verify=expected,c_diagnostics -Wmissing-format-attribute Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang\test\Sema\attr-format-missing.c
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\clang.exe' -cc1 -internal-isystem 'Z:\b\llvm-clang-x86_64-sie-win\build\lib\clang\19\include' -nostdsysteminc -fsyntax-only -verify=expected,c_diagnostics -Wmissing-format-attribute 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang\test\Sema\attr-format-missing.c'
# .---command stderr------------
# | error: 'c_diagnostics-warning' diagnostics seen but not expected: 
# |   File Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang\test\Sema\attr-format-missing.c Line 391: incompatible pointer types passing 'char *' to parameter of type 'struct __va_list_tag *'
# | error: 'c_diagnostics-note' diagnostics seen but not expected: 
# |   File Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang\test\Sema\attr-format-missing.c Line 30: passing argument to parameter here
# | 2 errors generated.
# `-----------------------------
# error: command failed with exit status: 1

--

********************


```

https://github.com/llvm/llvm-project/pull/70024