Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Update macros for multiple ABI support from NetBSD.
Also update SZREG define in ucontext

Using svn cp rather than cp to copy these files over had the benefit
of preserving their history. It had the problem that it also copied
over mergeinfo data. Since we're retiring the projects/mips branch,
I'm removing the svn:mergeinfo property from them all.

Submitted by: jhb

Merge from projects/mips to head by hand:

Copy over new cdefs.h..

Bring in cdefs.h from NetBSD to define ABI goo.

Obtained from: NetBSD