Skip build of testegl on RPI if no brcmegl dependency available
I want to build gst-omx using gst-build for RPi4 due to need for
By default build of gst-omx implies build of
The example should be linked to
brcmegl library for RPi target,
which is deprecated and not properly functioning on RPi4.
Moreover providing pkg-config path to RPi-specific libs in order to compile testegl example causes several build errors in
Workaround for the case should be disabling building of examples.
But due to bug in in meson it's not possible to disable examples only for
gst-omx, only for all the GStreamer subporjects.
It's suggested to skip build of testegl in case no RPi-specific libs found.