Format error by value

- Use `%v` verb to format errors.
- Give `param` constant in portallocator some better name.

Signed-off-by: Michal Minar <miminar@redhat.com>
Upstream-commit: 210ab030bc3dab7bcf8f7252f2f9facb5a26cb6b
Component: engine

components/engine/vendor/src/github.com/docker/libcontainer/user/user_test.go

@@ -198,7 +198,7 @@ this is just some garbage data
 
 		execUser, err := GetExecUser(test.ref, &defaultExecUser, passwd, group)
 		if err != nil {
-			t.Logf("got unexpected error when parsing '%s': %s", test.ref, err.Error())
+			t.Logf("got unexpected error when parsing '%s': %v", test.ref, err)
 			t.Fail()
 			continue
 		}
@@ -337,7 +337,7 @@ this is just some garbage data
 
 		execUser, err := GetExecUser(test.ref, &defaultExecUser, passwd, group)
 		if err != nil {
-			t.Logf("got unexpected error when parsing '%s': %s", test.ref, err.Error())
+			t.Logf("got unexpected error when parsing '%s': %v", test.ref, err)
 			t.Fail()
 			continue
 		}