Reland "[compiler-rt][aarch64] Add SME ABI support routines." (#68875)

Resolved issue with green dragon build by fixing relocations for
MachO/Darwin which doesn't compile without @page/@pageoff directives.

Also silenced a warning about constructor(90) priority being < 101,
which is reserved for the implementation. In this case, we're compiling
the implementation so we should be able to use 90.

This reverts commit 072713ad.