Try to fix the build with MSVC 2015 by disabling sized deallocation

I can't actually test this properly because uninstalling MSVC 2015 CTP 6
and reinstalling the 2015 RC takes hours. I can only verify that this
doesn't mess up MSVC 2013 and 2015 CTP 6 builds, which is what I've
done.

Should fix PR23513.

llvm-svn: 237743