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)

Per Regents of the University of Calfornia letter, remove advertising
clause.

# If I've done so improperly on a file, please let me know.

Implement wcwidth() as an inline function.

Grab all the information we need about a character with one call to
__maskrune() instead of one direct call and one through iswprint().

Use modern-style arguments declaration

Write null wide-character as L'\0' like in other places

According to SUSv2, always return 0 for null wide-character code

Move internal defines from ctype.h here

Move wcwidth() to separate file, it doesn't belong to iswctype.c at all