Improve clang-format's c-style cast detection.

Before:
  x[(uint8) y];
  x = (uint8) y;
  void f() { x = (uint8) y; }
  #define AA(X) sizeof(((X *) NULL)->a)

After:
  x[(uint8)y];
  x = (uint8)y;
  void f() { x = (uint8)y; }
  #define AA(X) sizeof(((X *)NULL)->a)

llvm-svn: 183014