Fix typos in clang

Found via codespell -q 3 -I ../clang-whitelist.txt
Where whitelist consists of:

  archtype
  cas
  classs
  checkk
  compres
  definit
  frome
  iff
  inteval
  ith
  lod
  methode
  nd
  optin
  ot
  pres
  statics
  te
  thru

Patch by luzpaz! (This is a subset of D44188 that applies cleanly with a few
files that have dubious fixes reverted.)

Differential revision: https://reviews.llvm.org/D44188

llvm-svn: 329399
diff --git a/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp b/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
index 681e876..52b979c 100644
--- a/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
+++ b/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
@@ -6747,9 +6747,9 @@
    if (Ivar->getAccessControl() == ObjCIvarDecl::Private ||
        Ivar->getAccessControl() == ObjCIvarDecl::Package ||
        Class->getVisibility() == HiddenVisibility)
-     Visibility shoud be: HiddenVisibility;
+     Visibility should be: HiddenVisibility;
    else
-     Visibility shoud be: DefaultVisibility;
+     Visibility should be: DefaultVisibility;
   */
   
   Result += "\n";