clang-format: Fix incorrect &/* detection.

Before:
  STATIC_ASSERT((a &b) == 0);

After:
  STATIC_ASSERT((a & b) == 0);

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@204709 91177308-0d34-0410-b5e6-96231b3b80d8