MFC r359937:

Centralize compatability translation macros.

Copy the CP, PTRIN, etc macros from freebsd32.h into a sys/abi_compat.h
and replace existing definitation with includes where required. This
eliminates duplicate code and allows Linux and FreeBSD compatability
headers to be included in the same files.

Obtained from: CheriBSD
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D24275