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/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
index 28b843e..cc582b9 100644
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -624,7 +624,7 @@
                                               LValue lvalue, QualType type);
 
 /// Generate an Objective-C method.  An Objective-C method is a C function with
-/// its pointer, name, and types registered in the class struture.
+/// its pointer, name, and types registered in the class structure.
 void CodeGenFunction::GenerateObjCMethod(const ObjCMethodDecl *OMD) {
   StartObjCMethod(OMD, OMD->getClassInterface());
   PGO.assignRegionCounters(GlobalDecl(OMD), CurFn);