Improve identification of c-style casts.

A ")" before any of "=", "{" or ";" won't be a cast. This fixes issues
with the formatting of unnamed parameters.

Before: void f(int *){}
After:  void f(int *) {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172349 91177308-0d34-0410-b5e6-96231b3b80d8