Remove -Wunused-member-function from the 'Extra' diagnostic group too; llvm uses it.

This effectively disables -Wunused-member-function for building llvm/clang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111356 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed