[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

1897

(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 (!File) {
+      if (LangOpts.SpellChecking && !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,