gst-libav: update from 1.2.3 to 1.2.4

(cherry picked from commit 6324296900361fc06741fef8d548b0c4ad145999)
gst-plugins-bad: update from 1.2.3 to 1.2.4

(cherry picked from commit 98dd37afad10a68acc0d581a907ecb1637ae1bd6)
gst-plugins-good: update from 1.2.3 to 1.2.4

(cherry picked from commit cd5702da472720470d0356faf472a46b18fba111)
gst-plugins-ugly: update from 1.2.3 to 1.2.4

(cherry picked from commit 69c4dae3794193dda650a2d917b7a4bf0265b946)
gstreamer: update from 1.2.3 to 1.2.4

(cherry picked from commit b57c9ed9d5f446cc829c70f4101a956dd6dfe47e)
gst-plugins-bad: build with wildmidi and fluidsynth

remove timidity, the plugin does not build at all

(cherry picked from commit 388d32d966fc25c4c3bf355f41e00eea031454dd)
gst-plugins-base: update from 1.2.3 to 1.2.4 (in #2440)

(cherry picked from commit fead8862d698e43ead49e553ad7d7120c84edfaf)