tests: remove spurious leftover use of 'Exit' Issue revealed by the 'sc_tests_Exit_not_exit' maintainer check. Commit 'v1.12.4-184-g9fed1c8' in master made the same fix basically, but we mistakenly applied it to master only, rather than to maint. * t/per-target-flags.sh: Here. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>