configure: check for ump/ump.h

And disable building ump when it is not there.

Signed-off-by: Luc Verhaegen <libv@skynet.be>
ump: set ump_alternative_fb_secure_id to invalid

This avoids a kernel oops due to the badly implemented and badly
checked ump interface.

Signed-off-by: Luc Verhaegen <libv@skynet.be>