[clang] Add fine-grained `__has_feature()` cutout (PR #170822)

[Vitaly Buka via cfe-commits]

================
@@ -2421,6 +2404,14 @@ def fsanitize_EQ : CommaJoined<["-"], "fsanitize=">, Group<f_clang_Group>,
                             "or suspicious behavior. See user manual for available checks">;
 def fno_sanitize_EQ : CommaJoined<["-"], "fno-sanitize=">, Group<f_clang_Group>,
                       Visibility<[ClangOption, CLOption]>;
+def fsanitize_ignore_for_ubsan_feature_EQ
+    : CommaJoined<["-"], "fsanitize-ignore-for-ubsan-feature=">,
----------------
vitalybuka wrote:

why do we need the flag?

https://github.com/llvm/llvm-project/pull/170822