test.sh: Don't abort on failed test

This behavior severely limits the usefulness of the test suite. An option
to configure it would still be nice.

Change-Id: I2bc96a043cc4ec76f334a3bfe48967703ef1be5e
Reviewed-on: https://code.wireshark.org/review/16890
Reviewed-by: João Valverde <j@v6e.pt>

test/test-backend.sh

@@ -302,8 +302,6 @@ test_step_failed() {
 
 	$color_reset
 
-	exit 1
-
 	# XXX - add a mechanism to optionally stop here
 }