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/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index dea1c2e..bae2783 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -6384,7 +6384,7 @@
         Expr::Classification ObjectClassification;
         if (Args.size() > 0) {
           if (Expr *E = Args[0]) {
-            // Use the explit base to restrict the lookup:
+            // Use the explicit base to restrict the lookup:
             ObjectType = E->getType();
             ObjectClassification = E->Classify(Context);
           } // .. else there is an implit base.
@@ -6412,7 +6412,7 @@
         QualType ObjectType;
         Expr::Classification ObjectClassification;
         if (Expr *E = Args[0]) {
-          // Use the explit base to restrict the lookup:
+          // Use the explicit base to restrict the lookup:
           ObjectType = E->getType();
           ObjectClassification = E->Classify(Context);
         } // .. else there is an implit base.
@@ -11915,7 +11915,7 @@
       << Fn->getSourceRange();
     CandidateSet->NoteCandidates(SemaRef, OCD_AllCandidates, Args);
 
-    // We emitted an error for the unvailable/deleted function call but keep
+    // We emitted an error for the unavailable/deleted function call but keep
     // the call in the AST.
     FunctionDecl *FDecl = (*Best)->Function;
     Fn = SemaRef.FixOverloadedFunctionReference(Fn, (*Best)->FoundDecl, FDecl);
@@ -12395,7 +12395,7 @@
       if (Opc == BO_Comma)
         break;
 
-      // For class as left operand for assignment or compound assigment
+      // For class as left operand for assignment or compound assignment
       // operator do not fall through to handling in built-in, but report that
       // no overloaded assignment operator found
       ExprResult Result = ExprError();