isspace_l: New module.

isspace_l: New module.

* lib/ctype.in.h: (isspace_l): New declaration.
* lib/isspace_l.c: New file.
* m4/isspace_l.m4: New file.
* m4/ctype_h.m4 (gl_CTYPE_H): Test for isspace_l.
(gl_CTYPE_H_REQUIRE_DEFAULTS): Initialize GNULIB_ISSPACE_L.
(gl_CTYPE_H_DEFAULTS): Initialize HAVE_ISSPACE_L.
* modules/ctype-h (Makefile.am): Substitute GNULIB_ISSPACE_L,
HAVE_ISSPACE_L.
* modules/isspace_l: New file.
* tests/test-ctype-h-c++.cc: Check declaration of isspace_l.
* doc/posix-functions/isspace_l.texi: Mention the new module.