Test suite should use endianness detection built in to vstruct

vstruct/io/endianness.lua

@@ -17,10 +17,12 @@ end
 
 function e.big()
     endianness = "big"
+    return endianness
 end
 
 function e.little()
     endianness = "little"
+    return endianness
 end
 
 -- select whichever endianness the host system uses

vstruct/test/common.lua

@@ -92,9 +92,9 @@ function test.report()
 	return allfailed
 end
 
--- determine host endianness - HACK HACK HACK
+-- determine host endianness
 function test.bigendian()
-    return string.byte(string.dump(function() end)) == 0x00
+    return require "vstruct.io" ("endianness", "host") == "big"
 end
 
 return test