waf: fix build on AIX7

the same works for AIX 5,6,7 so leave away the version specifics (as autoconf build did)

Signed-off-by: Christian Ambach <ambi@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
waf: add --without-gettext option

Signed-off-by: Christian Ambach <ambi@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
waf: consolidate libintl related checks

consolidate the dealing with functions from libintl and the
handling of checking if libiconv is required or not
to a common place in lib/replace

also add a new samba_intl subsystem that has dependencies
on the appropriate set of libraries (libintl, libintl+libiconv or none)
that can be used as a general dependency by code that depends
on the internationalization libraries

Signed-off-by: Christian Ambach <ambi@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
waf: replace dependency to libintl with samba_intl

Signed-off-by: Christian Ambach <ambi@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

Autobuild-User(master): Christian Ambach <ambi@samba.org>
Autobuild-Date(master): Mon Aug 12 00:46:34 CEST 2013 on sn-devel-104