[NFC] Rename lit feature to '-fsized-deallocation' for consistency

The '-faligned-allocation' flag uses a feature with the same name (with a
leading dash).

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@347367 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed