add minimal test

Author: mohawk2

MANIFEST

@@ -3,3 +3,4 @@ MANIFEST
 Makefile.PL
 examples/troll.pl
 lib/NativeCall.pm
+t/basic.t

t/basic.t

@@ -0,0 +1,8 @@
+use strict;
+use warnings;
+use Test::More tests => 1;
+
+use parent qw(NativeCall);
+
+sub fmax :Args(double, double) :Native :Returns(double) {}
+is fmax(2.0, 3.0), 3.0;