mate-base/mate-panel: depend on min mate-desktop matching ${PV}

Depend on >=mate-desktop-$(ver_cut 1-2) to avoid build failures for now
as a quick workaround.

The maintainers should check whether each package really needs it and
also consider a possible QA check in the eclass given some of them
seem to have a pattern in configure.ac for this, but given the bug has
been open for a whlie, I'd rather have some of the deps be unnecessarily
tight (not that it's even that tight) than as-it-was.

Note that couldn't use ${MATE_BRANCH} as it says:
> # Major and minor numbers of the version number, unless live.
> # If live ebuild, will be set to '9999'.
which made me wonder if it's actually meant to be 1-2 or 1-3 in ver_cut
or what.

Anyway, in summary:
* Apply a fix which makes things better, even if it's slightly overkill;
* Someone needs to audit these to find the actual minimum versions
  (some truly do need this, some need just something older, although
  unclear if upstream carefully update these or ont);
* A QA check may be wise.

Bug: https://bugs.gentoo.org/935279
Bug: https://bugs.gentoo.org/936079
Signed-off-by: Sam James <sam@gentoo.org>

mate-base/mate-panel/mate-panel-1.28.1.ebuild

@@ -27,7 +27,7 @@ COMMON_DEPEND="
 	dev-libs/libxml2:2
 	>=gnome-base/dconf-0.13.4
 	>=gnome-base/dconf-editor-43.0
-	>=mate-base/mate-desktop-1.28.0
+	>=mate-base/mate-desktop-$(ver_cut 1-2)
 	>=mate-base/mate-menus-1.28.0
 	>=sys-apps/dbus-1.1.2
 	>=x11-libs/cairo-1.0.0[X?]