recipes-xfce/libxfce4ui: depends and autotools fixes

Note: this patch (v3) obseletes previous versions

libxfce4ui_4.10.0.bb: Upstream changes required autotools and gettext (intl)
fixes, as well as moving the autogen stuff to a separate task.  Full depends
were also added (2 were converted to PACKAGECONFIG options) along with a
vendor config option.

Signed-off-by: Stephen Arnold <stephen.arnold42@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>