Linux 3.7 compat: delayed_work_timer_fn is now GPL-exported

This adds delayed_work_timer_fn() to the list of GPL-exported symbols
this seems to use. Binaries probably cannot be legally redistributed,
but restoring compatibility will open the door to eliminating these
dependencies through refactoring.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Linux 3.8 compat: Some probe locations have been removed

sdt_add_locator is being called against some things that no longer
exist. I am adding preprocessor directives to fix that.

Signed-off-by: Richard Yao <ryao@gentoo.org>