gbm: dlopen libglapi so gbm_create_device works

gbm: dlopen libglapi so gbm_create_device works

Dri driver libs are not linked to pull in libglapi so gbm_create_device()
fails when it tries to dlopen them (unless the application is linked
with something that does pull in libglapi, like libGL).
Until dri drivers can be fixed properly, dlopen libglapi before trying
to dlopen them.

Cc: "10.5 10.6" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Frank Henigman <fjhenigman@google.com>
[Emil Velikov: Drop misleading bugzilla link, mention that libname differs]
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
(cherry picked from commit 828f13330c9384f2b55c8b0f962d93a74ecd0601)