xwayland/glx: Enable sRGB fbconfigs

We turn this on if the GL underneath us can enable GL_FRAMEBUFFER_SRGB.
We do try to generate both capable and incapable configs, which is to
keep llvmpipe working until the client side gets smarter about its srgb
capabilities.
5 jobs for glx-egl-srgb-fbconfigs in 6 minutes and 21 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Docker Image
passed debian-buster #13947758

00:00:15

 
  Build And Test
passed autotools #13947759

00:06:05

passed meson #13947760

00:02:24

passed meson-noglamor #13947761

00:01:36

passed mingw-cross-build #13947762

00:00:29