Add core-utils to backend-sql test LDADD

Needed for gnc_core_prefs_get_namespace_regexp and gnc_core_prefs_get_long_version

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23170 57a11ea4-9604-0410-9ed3-97b8803252fd