lua http: use us_tostring() to fix locale issues with decimals

The function is a bit ugly but it's difficult to do this using
pure arithmetic.

Fixes #6378

share/lua/intf/modules/common.lua

@@ -68,6 +68,13 @@ function us_tonumber(str)
     return s * (tonumber(i) + tonumber(d)/(10^string.len(d)))
 end
 
+-- tostring() for decimals number, using a dot as decimal separator
+-- regardless of the system locale 
+function us_tostring(n)
+    s = tostring(n):gsub(",", ".", 1)
+    return s
+end
+
 -- strip leading and trailing spaces
 function strip(str)
     return string.gsub(str, "^%s*(.-)%s*$", "%1")

share/lua/intf/modules/httprequests.lua

@@ -24,6 +24,7 @@
 
 module("httprequests",package.seeall)
 
+local common = require ("common")
 local dkjson = require ("dkjson")
 
 
@@ -197,6 +198,8 @@ end
 function xmlString(s)
   if (type(s)=="string") then
       return vlc.strings.convert_xml_special_chars(s)
+  elseif (type(s)=="number") then
+      return common.us_tostring(s)
   else
       return tostring(s)
   end