meson: Detect opengl api from -base .pc files correctly (1.14 backport)
Detect opengl api from -base .pc files correctly.
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. This could lead to build failures when building -bad with meson against a -base that was built with autotools. The mismatch has now been rectified but we will still check the old one for backwards compatibility.
Fixes #871 (closed)