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/StaticAnalyzer/Checkers/PointerArithChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
index 63f82b2..af24284 100644
--- a/clang/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp
@@ -112,7 +112,7 @@
 }
 
 /// Checks whether a region is the part of an array.
-/// In case there is a dericed to base cast above the array element, the
+/// In case there is a derived to base cast above the array element, the
 /// Polymorphic output value is set to true. AKind output value is set to the
 /// allocation kind of the inspected region.
 const MemRegion *PointerArithChecker::getArrayRegion(const MemRegion *Region,