lib/drmtest: don't complete fixtures with a longjmp

lib/drmtest: don't complete fixtures with a longjmp

Longjmp creates havoc with stack variables of the current stackframe.
And since fixtures should be used to set up such variables creating
havoc isn't a great idea. With this I can revert a bunch of
bogus patches I've done to paper over this by moving stack variables
to be global.

The same issue is actually a feature for subtest blocks since subtests
should be independant anyway.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>