lib/interval_tree_test.c: make test options module parameters

Allows for more flexible debugging.

Link: http://lkml.kernel.org/r/20170518174936.20265-3-dave@stgolabs.net


Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>