Update polyfills

Author: levno-710

src/prometheus.lua

@@ -12,7 +12,7 @@ end
 local oldPkgPath = package.path;
 package.path = script_path() .. "?.lua;" .. package.path;
 
--- Math.random Fix
+-- Math.random Fix for Lua5.1
 -- Check if fix is needed
 if not pcall(function()
     return math.random(1, 2^40);
@@ -38,6 +38,14 @@ end) then
     end
 end
 
+-- newproxy polyfill
+_G.newproxy = _G.newproxy or function(arg)
+    if arg then
+        return setmetatable({}, {});
+    end
+    return {};
+end
+
 
 -- Require Prometheus Submodules
 local Pipeline  = require("prometheus.pipeline");

src/prometheus/util.lua

@@ -243,7 +243,7 @@ end
 
 
 local function readonly(obj)
-	local r = newproxy and newproxy(true) or setmetatable({}, {});
+	local r = newproxy(true);
 	getmetatable(r).__index = obj;
 	return r;
 end