[clang] [llvm] Make sanitizer special case list slash-agnostic (PR #149886)

[Vitaly Buka via llvm-commits]

================
@@ -595,10 +612,18 @@ bool WarningsSpecialCaseList::isDiagSuppressed(diag::kind DiagId,
       SrcEntriesIt->getValue();
   // We also use presumed locations here to improve reproducibility for
   // preprocessed inputs.
-  if (PresumedLoc PLoc = SM.getPresumedLoc(DiagLoc); PLoc.isValid())
-    return globsMatches(
-        CategoriesToMatchers,
-        llvm::sys::path::remove_leading_dotslash(PLoc.getFilename()));
+  if (PresumedLoc PLoc = SM.getPresumedLoc(DiagLoc); PLoc.isValid()) {
+    if (CanonicalizePaths) {
----------------
vitalybuka wrote:

is going to be common thing for all users of 
```
if (CanonicalizePaths) {
      return globsMatches(
          CategoriesToMatchers,
          llvm::sys::path::convert_to_slash(
              llvm::sys::path::remove_leading_dotslash(PLoc.getFilename())));
    } else {
      return globsMatches(
          CategoriesToMatchers,
          llvm::sys::path::remove_leading_dotslash(PLoc.getFilename()));
    }
```

Lets put that thing into `SpecialCaseList::NormalizePath()`


https://github.com/llvm/llvm-project/pull/149886