MFC r292578:

MFC r292578:

Don't dump core files with lib/libc/ssp/ssp_test and lib/libc/gen/assert_test

The default `sysctl kern.corefile` value is compatible with `kyua test` (FreeBSD
will dump to the current directory). If it's set to an absolute path however,
`kyua test` will not be able to clean up the corefiles after the fact

The corefiles have little value when testing the behavior of feature behavior,
so just disable corefile generation

Obtained from: Isilon OneFS (^/onefs/head@r511419)
Sponsored by: EMC / Isilon Storage Division

git-svn-id: svn://svn.freebsd.org/base/stable/10@292852 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f