aarch64: use PTR_ARG and SIZE_ARG instead of DELOUSE

DELOUSE was added to asm code to make them compatible with non-LP64
ABIs, but it is an unfortunate name and the code was not compatible
with ABIs where pointer and size_t are different. Glibc currently
only supports the LP64 ABI so these macros are not really needed or
tested, but for now the name is changed to be more meaningful instead
of removing them completely.

Some DELOUSE macros were dropped: clone, strlen and strnlen used it
unnecessarily.

The out of tree ILP32 patches are currently not maintained and will
likely need a rework to rebase them on top of the time64 changes.