Use Gnulib ACL implementation, for benefit of Solaris etc.

Use Gnulib ACL implementation, for benefit of Solaris etc.

* configure.ac: Remove -with-acl option, since Gnulib does that for
us now.
(LIBACL_LIBS): Remove; no longer needed.
* lib/Makefile.am (CLEANFILES, SUFFIXES): New (empty) macros,
for the benefit of the new ACL implementation.
* lib/makefile.w32-in (GNULIBOBJS): Add $(BLD)/acl-errno-valid.$(O).
($(BLD)/acl-errno-valid.$(O)): New rule.
* lib/acl-errno-valid.c, lib/acl-internal.h, lib/acl.h:
* lib/acl_entries.c, lib/errno.in.h, lib/file-has-acl.c:
* lib/qcopy-acl.c, lib/qset-acl.c, m4/acl.m4, m4/errno_h.m4:
New files, taken from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* admin/merge-gnulib (GNULIB_MODULES): Add qacl.
(GNULIB_TOOL_FLAGS): Do not avoid errno.
* etc/NEWS: Emacs is no longer limited to POSIX ACLs.  --disable-acl,
not --without-acl, since we're now using Gnulib's implementation.
* nt/config.nt (HAVE_ACL_SET_FILE): Rename from HAVE_POSIX_ACL.
* nt/inc/ms-w32.h (EOPNOTSUPP): New macro.
* src/Makefile.in (LIB_ACL): New macro.
(LIBACL_LIBS): Remove.
(LIBES): Use LIB_ACL, not LIBACL_LIBS.
* src/fileio.c: Include <acl.h>.
Use HAVE_ACL_SET_FILE rather than HAVE_POSIX_ACL.
(ACL_NOT_WELL_SUPPORTED): Remove.  All uses replaced by
!acl_errno_valid.
(Fcopy_file) [!WINDOWSNT]: Use qcopy_acl instead of rolling
it ourselves.

Fixes: debbugs:14295