revisions API users: use release_revisions() with UNLEAK()

Use a release_revisions() with those "struct rev_list" users which
already "UNLEAK" the struct. It may seem odd to simultaneously attempt
to free() memory, but also to explicitly ignore whether we have memory
leaks in the same.

As explained in preceding commits this is being done to use the
built-in commands as a guinea pig for whether the release_revisions()
function works as expected, we'd like to test e.g. whether we segfault
as we change it. In subsequent commits we'll then remove these
UNLEAK() as the function is made to free the memory that caused us to
add them in the first place.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/diff-index.c

@@ -71,5 +71,7 @@ int cmd_diff_index(int argc, const char **argv, const char *prefix)
 	}
 	result = run_diff_index(&rev, option);
 	UNLEAK(rev);
-	return diff_result_code(&rev.diffopt, result);
+	result = diff_result_code(&rev.diffopt, result);
+	release_revisions(&rev);
+	return result;
 }

builtin/diff.c

@@ -595,6 +595,7 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 	if (1 < rev.diffopt.skip_stat_unmatch)
 		refresh_index_quietly();
 	UNLEAK(rev);
+	release_revisions(&rev);
 	UNLEAK(ent);
 	UNLEAK(blob);
 	return result;