lib: s/drmtest_dumb_aub/igt_aub_dump_enabled/

This is prep work to extract a new igt aux library with all kinds
of random stuff. Also give it a bit a more suitable name to
indicate that this is just a flag and doesn't do the aub dumping
itself.

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

lib/drmtest.c

@@ -329,7 +329,7 @@ bool igt_env_set(const char *env_var, bool default_value)
 	return atoi(val) != 0;
 }
 
-bool drmtest_dump_aub(void)
+bool igt_aub_dump_enabled(void)
 {
 	static int dump_aub = -1;