- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r271651, r271719, r272138, r272457, r272845, r275476, r275518, r275614,
r275819, r276176, r278154, r278160, r278339, r279127, r279240, r279491,
r279493, r279856, r283032, r284423, r284426, r284427, r284428

Merge changes to libm from the past 9 months. This includes improvements
to the Bessel functions and adds the C99 function lgammal.

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

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

In the line
#pragma STDC CX_LIMITED_RANGE ON
the "ON" needs to be in caps. gcc doesn't understand this pragma
anyway and assumes it is always on in any case, but icc supports
it and cares about the case.

- Correct the range check in the double version to catch negative values
that would overflow.
- Style fixes and improved handling of NaNs suggested by bde.

Implement and document csqrt(3) and csqrtf(3).