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/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index b5583d1..9cc1bd5 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -7865,7 +7865,7 @@
       return false;
 
     case TSK_ExplicitInstantiationDeclaration:
-      // We're explicity instantiating a definition for something for which we
+      // We're explicitly instantiating a definition for something for which we
       // were previously asked to suppress instantiations. That's fine.
 
       // C++0x [temp.explicit]p4: