Fixes bug in string literal alignment.

We now indent the following correctly:
1. some + "literal" /* comment */
          "literal";
2. breaking string literals after which we have another string literal.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175628 91177308-0d34-0410-b5e6-96231b3b80d8