lib: another attempt at Coverity false positives

lib: another attempt at Coverity false positives

Typesafe hash tables do this:

	assume((tabshift) >= 2 && (tabshift) <= 33);
	(val) >> (33 - (tabshift));

Sadly, Coverity currently ignores assume() and says:
	[...] right shifting by more than 31 bits has undefined behavior.
	The shift amount, "33 - h->hh.tabshift", is 33.

Let's see if Coverity understands this can't happen...

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>