[PATCH] FreeBSD AArch64 support

[Tim Northover]

> FreeBSD on 64-bit architectures uses an LP64 data model. This will
> make size_t an unsigned long and wchar_t an unsigned word which would
> make it an unsigned int.

It could also be an "unsigned long long" within the LP64 model, again
visible in name mangling and various template argument deduction
edge-cases (e.g. are separate foo<size_t> and foo<unsigned long>
specialisations permitted?)

Cheers.

Tim.