There was a mismatch between the .pc files generated by
autotools and by meson that would lead to meson not detecting
that opengl api is available even though it is, if -base was
built with autotools. The mismatch has now been rectified in
-base, but we still check the old one for backwards
compatibility.

This is mostly for consistency, this problem didn't seem
to affect anything in -good.

See gstreamer/gst-plugins-bad#871