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/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index b5c387b..c2f1422 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -8001,7 +8001,7 @@
     }
 
     case SK_OCLSamplerInit: {
-      // Sampler initialzation have 5 cases:
+      // Sampler initialization have 5 cases:
       //   1. function argument passing
       //      1a. argument is a file-scope variable
       //      1b. argument is a function-scope variable