Fix bug in the adjustment to existing lines.

Before (if only the second line was reformatted):
void f() {}
          void g() {}

After:
void f() {}
void g() {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174978 91177308-0d34-0410-b5e6-96231b3b80d8