egl/dri2: Add reference count for dri2_egl_display

egl/dri2: Add reference count for dri2_egl_display

android.opengl.cts.WrapperTest#testGetIntegerv1 CTS test calls
eglTerminate, followed by eglReleaseThread. A similar case is
observed in this bug: https://bugs.freedesktop.org/show_bug.cgi?id=69622,
where the test calls eglTerminate, then eglMakeCurrent(dpy, NULL, NULL, NULL).

With the current code, dri2_dpy structure is freed on eglTerminate
call, so the display is not initialized when eglReleaseThread calls
MakeCurrent with NULL parameters, to unbind the context, which
causes a a segfault in drv->API.MakeCurrent (dri2_make_current),
either in glFlush or in a latter call.

eglTerminate specifies that "If contexts or surfaces associated
with display is current to any thread, they are not released until
they are no longer current as a result of eglMakeCurrent."

However, to properly free the current context/surface (i.e., call
glFlush, unbindContext, driDestroyContext), we still need the
display vtbl (and possibly an active dri dpy connection). Therefore,
we add some reference counter to dri2_egl_display, to make sure
the structure is kept allocated as long as it is required.

One drawback of this is that eglInitialize may not completely reinitialize
the display (if eglTerminate was called with a current context), however,
this seems to meet the EGL spec quite well, and does not permanently
leak any context/display even for incorrectly written apps.

Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
(cherry picked from commit 9ee683f877b283020c6f24776236f1145cb7a4ea)

Squashed with commit

egl/dri2: dri2_make_current: Release previous context's display

eglMakeCurrent can also be used to change the active display. In that
case, we need to decrement ref_count of the previous display (possibly
destroying it), and increment it on the next display.

Also, old_dsurf/old_rsurf cannot be non-NULL if old_ctx is NULL, so
we only need to test if old_ctx is non-NULL.

v2: Save the old display before destroying the context.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97214
Fixes: 9ee683f877 (egl/dri2: Add reference count for dri2_egl_display)
Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Reported-by: Alexandr Zelinsky <mexahotabop@w1l.ru>
Tested-by: Alexandr Zelinsky <mexahotabop@w1l.ru>
Reviewed-and-Tested-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
(cherry picked from commit 78e3cea4197802253401766fc44362786898e024)

Squashed with commit

egl/dri2: dri2_initialize: Do not reference-count TestOnly display

In the case where dri2_initialize is called with a TestOnly display,
the display is not actually initialized, so dri2_egl_display always
fails, and we cannot do any reference counting.

Fixes piglit spec@egl_khr_create_context@verify gl flavor (reproducible
with LIBGL_ALWAYS_SOFTWARE=1).

Fixes: 9ee683f877 (egl/dri2: Add reference count for dri2_egl_display)
Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Reported-by: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
(cherry picked from commit 4f3f8bb59dd98e39c363fe47a55a7f97e7df9f4b)