Don't recognize unnamed pointer parameters as casts.

This fixes llvm.org/PR15061.

Before: virtual void f(int *)const;
After:  virtual void f(int *) const;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175960 91177308-0d34-0410-b5e6-96231b3b80d8