Remove superseeded option.

The -invert-pointer-binding option will be superseeded by my next
cfe-commit. Instead of explicitly overwriting this flag, clang-format
can then be configured to auto-detect certain style-options based on the
input file.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@174503 91177308-0d34-0410-b5e6-96231b3b80d8