Refactoring: replaced (*(I + x)) with I[x].

Summary: Pure refactoring, no semantic changes intended.

Reviewers: klimek

Reviewed By: klimek

CC: cfe-commits, klimek

Differential Revision: http://llvm-reviews.chandlerc.com/D2220

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195128 91177308-0d34-0410-b5e6-96231b3b80d8