Don't append newline for varnishtest -p

Original patch from @joshuaspence.

Closes #2262

bin/varnishtest/tests/r02262.vtc

+varnishtest "varnishtest -p"
+
+shell {
+cat >_.vtc <<EOF
+varnishtest -p
+varnish v1 -cliexpect 42 "param.show default_ttl"
+EOF
+
+exec varnishtest -v -t 5 -p default_ttl=42 _.vtc
+}

bin/varnishtest/vtc_main.c

@@ -627,7 +627,7 @@ main(int argc, char * const *argv)
 			break;
 		case 'p':
 			VSB_printf(params_vsb, " -p ");
-			VSB_quote(params_vsb, optarg, -1, VSB_QUOTE_NONL);
+			VSB_quote(params_vsb, optarg, -1, 0);
 			break;
 		case 'q':
 			if (vtc_verbosity > 0)