meson: display OMX target when configuring

I'm adding more gst-omx CI (
gstreamer/gst-ci#20 ) having the
OMX targets displayed in the logs makes things clearer.
9 jobs for msg-target in 28 minutes and 3 seconds (queued for 1 second)
Status Name Job ID Coverage
  Preparation
passed gst indent #1287322

00:00:16

passed manifest #1287321

00:00:42

 
  Build
passed build clang fedora x86_64 #1287327

00:06:18

passed build fedora x86_64 #1287323

00:08:03

passed build nodebug fedora x86_64 #1287324

00:04:55

passed build static fedora x86_64 #1287325

00:22:51

passed build static nodebug fedora x86_64 #1287326

00:04:55

 
  Integrate
passed documentation #1287455

00:04:29

failed documentation #1287328

00:05:34