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/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index 5584e18..3746bda 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -2884,7 +2884,7 @@
                                  IMPDecl, PI, IncompleteImpl, false,
                                  WarnCategoryMethodImpl);
 
-    // FIXME. For now, we are not checking for extact match of methods
+    // FIXME. For now, we are not checking for exact match of methods
     // in category implementation and its primary class's super class.
     if (!WarnCategoryMethodImpl && I->getSuperClass())
       MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,