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/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 429bd18..5daa4e9 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -777,7 +777,7 @@
   /// Return the llvm::Constant for the address of the given global variable.
   /// If Ty is non-null and if the global doesn't exist, then it will be created
   /// with the specified type instead of whatever the normal requested type
-  /// would be. If IsForDefinition is true, it is guranteed that an actual
+  /// would be. If IsForDefinition is true, it is guaranteed that an actual
   /// global with type Ty will be returned, not conversion of a variable with
   /// the same mangled name but some other type.
   llvm::Constant *GetAddrOfGlobalVar(const VarDecl *D,
@@ -1178,7 +1178,7 @@
     DeferredVTables.push_back(RD);
   }
 
-  /// Emit code for a singal global function or var decl. Forward declarations
+  /// Emit code for a single global function or var decl. Forward declarations
   /// are emitted lazily.
   void EmitGlobal(GlobalDecl D);