No functional change.  Renaming a variable in RecordLayoutBuilder and 
improving comments to make documentation more accurate.

Differential Revision:http://llvm-reviews.chandlerc.com/D2172



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194609 91177308-0d34-0410-b5e6-96231b3b80d8