fix buildlinking or bump BUILDLINK_API_DEPENDS.startup-notification?

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

I see the startup-notification's buildlink3.mk added:
.include "../../x11/libxcb/buildlink3.mk"
.include "../../x11/xcb-util/buildlink3.mk"

But the
BUILDLINK_API_DEPENDS.startup-notification+=startup-notification>=0.5
stayed the same.

I have an acceptable startup-notification version installed (0.9). So 
building pcmanfm which includes x11/startup-notification/buildlink3.mk 
fails with:

ERROR: xcb-util>=0.3.3 is not installed; can't buildlink files.

Simple fix is to bump BUILDLINK_API_DEPENDS.startup-notification.

The ERROR doesn't make it easy as it doesn't show what actually required 
this. Also why doesn't it try to install that if it knows it is needed?

For now I commented out the two includes above and pcmanfm builds for 
me.