trial: always use abspath

No actual failure known, but using the abspath will prevent further problems
when running a binary in its own run dir and passing trial paths to it.

Adjust test expectations.

Change-Id: Ia2ba876a42eef9122a92645edd1f28ddb56e6be3
diff --git a/selftest/trial_test.ok.ign b/selftest/trial_test.ok.ign
index 38a82ce..1a969de 100644
--- a/selftest/trial_test.ok.ign
+++ b/selftest/trial_test.ok.ign
@@ -1,2 +1,3 @@
 /tmp/[^/]*	[TMP]
 ....-..-.._..-..-..	[TIMESTAMP]
+'[^']*/trial_test	'[PATH]/trial_test