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

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

Implement xlocale APIs from Darwin, mainly for use by libc++. This adds a
load of _l suffixed versions of various standard library functions that use
the global locale, making them take an explicit locale parameter. Also
adds support for per-thread locales. This work was funded by the FreeBSD
Foundation.

Please test any code you have that uses the C standard locale functions!

Reviewed by: das (gdtoa changes)
Approved by: dim (mentor)

Merge gdtoa-20110304.

Vendor import of gdtoa 20081205.

Merge gdtoa 20080831. This fixes several bugs, including an infinite
loop pointed out by cognet@ that occurs when calling strtod() with a
string representing a number between DBL_MAX and 2*DBL_MAX, when the
rounding mode is anything other than the default.

This commit was generated by cvs2svn to compensate for changes in r165743,
which included commits to RCS files with non-trunk default branches.

Import of the latest gdtoa sources, which include fixes for minor
problems relating to NaNs and rounding.

Import new sources. The only material change in this update is to
add locale support for hexadecimal floating point conversions.

Noticed by: ache
Reviewed by: mike (mentor)

Import gdtoa sources dated 20030318, which contain several locale fixes.

Reviewed by: mike (mentor)

Initial import of David Gay's gdtoa library for conversion between
strings and floating point.