Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC the xlocale implementation.

Merged revisions: 227487,227753,227807,227818,227999,228002,228875,230156,231673,232498,232601,232620,232626,232926-232927,232929,232931,232935,233173,233600,234573,234578,235239

This currently defines __NO_TLS on ARM (unlike head), because the required
support function has not been MFC'd.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

The problem is: currently our single byte ctype(3) functions are broken
for wide characters locales in the argument range >= 0x80 - they may
return false positives.

Example 1: for UTF-8 locale we currently have:
iswspace(0xA0)==1 and isspace(0xA0)==1
(because iswspace() and isspace() are the same code)
but must have
iswspace(0xA0)==1 and isspace(0xA0)==0
(because there is no such character and all others in the range
0x80..0xff for the UTF-8 locale, it keeps ASCII only in the single byte
range because our internal wchar_t representation for UTF-8 is UCS-4).

Example 2: for all wide character locales isalpha(arg) when arg > 0xFF may
return false positives (must be 0).
(because iswalpha() and isalpha() are the same code)

This change address this issue separating single byte and wide ctype
and also fix iswascii() (currently iswascii() is broken for
arguments > 0xFF).
This change is 100% binary compatible with old binaries.

Reviewied by: i18n@

. Static'ize functions exported via function reference variables only.
. Replace inclusion of sys/param.h to sys/cdefs.h and sys/types.h where
appropriate.
. move _*_init() prototypes to mblocal.h, and remove these prototypes
from .c files
. use _none_init() in __setrunelocale() instead of duplicating code
. move __mb* variables from table.c to none.c allowing us to not to
export _none_*() externs, and appropriately remove them from mblocal.h

Ok'ed by: tjr

Move prototypes of various encoding-related functions into a new header
file to avoid extern'ing them all over the place.

Perform some basic validation of multibyte conversion state objects.

Fix a typo. I was locked out for two days from my machine.

Don't cast away const qualifiers.

Spotted by: bde

Allow partial multibyte characters to accumulate in conversion state
objects passed to mbrtowc(), mbsrtowcs(), and mbrlen(), as required
by C99.

Remove unused #includes.

Use __inline instead of inline.

Add gb2312 encoding.