Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

libc_r wasn't so tied to libc for 22 months.

We typically don't add trailing /'s.

Add code to emulate arithmetic, comparison and conversion operations
on long double, which are not implemented in hardware on any UltraSPARC
chip that I know of. This just calls into the existing floating point
emulator, which is still needed to emulate other floating point operations
in certain conditions. Without this gcc has to generate the quad floating
point instructions directly, which sometimes causes internal compiler
errors.

Reviewed by: tmm

Emulate ldq and stq (load/store long double) instructions. GCC has started
using these to load long doubles, but they aren't implemented in hardware
on (at least) UltraSPARC I and II machines.
Emulate popc in the user trap handler as well.
Re-arrange slightly to make support functions more accessible.

Reviewed by: tmm

Add userland floating point emulator code for sparc64. This is a port
of the (never committed) in-kernel version (with some optimizations and
cleanups), which in turn was ported from NetBSD.