Do not consider comments when adjusting to local indent style.

Before (when only reformatting "int b"):
int a; // comment
       // comment
       int b;

After:
int a; // comment
       // comment
int b;

This also fixes llvm.org/PR15433.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177524 91177308-0d34-0410-b5e6-96231b3b80d8