network-manager-applet: Fix missing DEPENDS and QA warnings.

This fixes:
| checking for ISO_CODES... no
| No package 'iso-codes' found.

and

| checking for GNOME_KEYRING... no
| configure: error: Package requirements (gnome-keyring-1) were not met:

Signed-off-by: Samuel Stirtzel <s.stirtzel@googlemail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>