Misc typos fixes in ./lib folder

Summary: Found via `codespell -q 3 -I ../clang-whitelist.txt -L uint,importd,crasher,gonna,cant,ue,ons,orign,ned`

Reviewers: teemperor

Reviewed By: teemperor

Subscribers: teemperor, jholewinski, jvesely, nhaehnle, whisperity, jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D55475

llvm-svn: 348755
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 3e7e8ac..39ae9ce 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -8129,7 +8129,7 @@
   // Also add the protocols associated with the LHS interface.
   Context.CollectInheritedProtocols(LHS->getInterface(), LHSProtocolSet);
 
-  // Add all of the protocls for the RHS.
+  // Add all of the protocols for the RHS.
   llvm::SmallPtrSet<ObjCProtocolDecl *, 8> RHSProtocolSet;
 
   // Start with the protocol qualifiers.