xwayland/present: Move wl_buffer check into xwl_glamor_check_flip

Keeps the glamor specific code together more.

Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>
5 jobs for xwl_glamor_eglstream_get_wl_buffer_for_pixmap-no-xwl_pixmap in 6 minutes and 18 seconds
Status Job ID Name Coverage
  Docker Image
passed #10819259
debian-buster

00:00:25

 
  Build And Test
passed #10819260
autotools

00:05:52

passed #10819261
meson

00:02:49

passed #10819262
meson-noglamor

00:02:01

passed #10819263
mingw-cross-build

00:00:50