cmake: check for the necessary symbols for test-segfault.c

cmake: check for the necessary symbols for test-segfault.c

If we don't check for them, and you have core dumps enabled, then
running this test under cmake is really annoying, because it leaves
lots of core dumps none of which are actually a problem.

The equivalent Autotools change (which added the actual code that
this relies on) is commit ae50d46, from fd.o#83772.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=83115
Reviewed-by: Ralf Habacker <ralf.habacker@freenet.de>