mkstemps, mkostemps: new modules

mkstemps, mkostemps: new modules

* modules/mkostemps: New module.
* modules/mkstemps: Likewise.
* lib/mkostemps.c (mkostemps): New file.
* lib/mkstemps.c (mkstemps): Likewise.
* m4/mkostemps.m4 (gl_FUNC_MKOSTEMPS): Likewise.
* m4/mkstemps.m4 (gl_FUNC_MKSTEMPS): Likewise.
* m4/stdlib_h.m4 (gl_STDLIB_H_DEFAULTS): Add witnesses.
* modules/stdlib (Makefile.am): Substitute them.
* lib/stdlib.in.h (mkostemps, mkstemps): Declare them.
* doc/glibc-functions/mkstemps.texi (mkstemps): New file.
* doc/glibc-functions/mkostemps.texi (mkostemps): Likewise.
* doc/gnulib.texi (Glibc stdlib.h): Include them.
* MODULES.html.sh (File system functions): Mention them.

Signed-off-by: Eric Blake <ebb9@byu.net>