Fix dereference formatting in for-loops.

Before: for (char **a = b; * a; ++a) {}
After:  for (char **a = b; *a; ++a) {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177037 91177308-0d34-0410-b5e6-96231b3b80d8