gst-plugins-package: add ${PN}-meta to PACKAGES directly instead from populate_packag...

gst-plugins-package: add ${PN}-meta to PACKAGES directly instead from populate_packages_prepend

* reported by Paul on OE ML
  http://lists.linuxtogo.org/pipermail/openembedded-devel/2011-April/031873.html
* and Crofton on IRC
* not really sure how PACKAGES_DYNAMIC can influence this, but now it
  works, -e output checked and doesn't look like space or something
  missing in PACKAGES
* tested on gst-plugins-base-meta
  SHR root@gjama /etc $ opkg info gst-plugins-base-meta
  Package: gst-plugins-base-meta
  Version: 0.10.32-r11.1.6
  Depends: gst-plugins-base, gst-plugins-base-apps, gst-plugins-base-meta, libgstcdda-0.10-0, libgstfft-0.10-0, libgstrtsp-0.10-0, libgstsdp-0.10-0, libgstapp-0.10-0, libgstnetbuffer-0.10-0, libgstvideo-0.10-0, libgstpbutils-0.10-0, libgstinterfaces-0.10-0, libgstriff-0.10-0, libgstaudio-0.10-0, libgsttag-0.10-0, libgstrtp-0.10-0, gst-plugin-adder, gst-plugin-video4linux, gst-plugin-audioconvert, gst-plugin-ffmpegcolorspace, gst-plugin-gdp, gst-plugin-videotestsrc, gst-plugin-videorate, gst-plugin-xvimagesink, gst-plugin-ximagesink, gst-plugin-vorbis, gst-plugin-libvisual, gst-plugin-audioresample, gst-plugin-cdparanoia, gst-plugin-volume, gst-plugin-videoscale, gst-plugin-decodebin2, gst-plugin-decodebin, gst-plugin-gio, gst-plugin-playbin, gst-plugin-pango, gst-plugin-audiorate, gst-plugin-subparse, gst-plugin-theora, gst-plugin-encodebin, gst-plugin-app, gst-plugin-audiotestsrc, gst-plugin-alsa, gst-plugin-ivorbisdec, gst-plugin-ogg, gst-plugin-tcp, gst-plugin-typefindfunctions
* notice that there is gst-plugins-base-meta in gst-plugins-base-meta's Depends,
  but opkg doesn't care

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>