[Preprocessor] Hide include typo correction behind SpellChecking.

[hokein]

Summary

Similar to Sema typo correction, the Preprocessor typo correction should
also be hidden behind the SpellChecking flag.

[sammccall]

lib/Lex/PPDirectives.cpp

1891

(just merge with existing if statement?)

[hokein]

Fix review comment.

lib/Lex/PPDirectives.cpp

if (!SuppressIncludeNotFoundError) {
             Filename <<
             FixItHint::CreateReplacement(Range, "\"" + Filename.str() + "\"");
         }
       }
 
       // Check for likely typos due to leading or trailing non-isAlphanumeric
       // characters
       StringRef OriginalFilename = Filename;
+      if (LangOpts.SpellChecking) {
         if (!File) {
           // A heuristic to correct a typo file name by removing leading and
           // trailing non-isAlphanumeric characters.
           auto CorrectTypoFilename = [](llvm::StringRef Filename) {
             Filename = Filename.drop_until(isAlphanumeric);
             while (!Filename.empty() && !isAlphanumeric(Filename.back())) {
               Filename = Filename.drop_back();
             }
             return Filename;
           };
           Filename = CorrectTypoFilename(Filename);
           File = LookupFile(
               FilenameLoc,
               LangOpts.MSVCCompat ? NormalizedPath.c_str() : Filename, isAngled,
               LookupFrom, LookupFromFile, CurDir,
               Callbacks ? &SearchPath : nullptr,
               Callbacks ? &RelativePath : nullptr, &SuggestedModule, &IsMapped);
           if (File) {
             SourceRange Range(FilenameTok.getLocation(), CharEnd);
             auto Hint = isAngled ? FixItHint::CreateReplacement(
                                        Range, "<" + Filename.str() + ">")
                                  : FixItHint::CreateReplacement(
                                        Range, "\"" + Filename.str() + "\"");
             Diag(FilenameTok, diag::err_pp_file_not_found_typo_not_fatal)
                 << OriginalFilename << Filename << Hint;
           }
         }
+      }
 
       // If the file is still not found, just go with the vanilla diagnostic
       if (!File)
         Diag(FilenameTok, diag::err_pp_file_not_found) << OriginalFilename
                                                        << FilenameRange;
     }
   }