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/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index bac538e..d063f03 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -870,7 +870,7 @@
   llvm_unreachable("Invalid TemplateSpecializationKind!");
 }
 
-/// This is a callback from Sema to tell us that that a particular vtable is
+/// This is a callback from Sema to tell us that a particular vtable is
 /// required to be emitted in this translation unit.
 ///
 /// This is only called for vtables that _must_ be emitted (mainly due to key