set RPC client environment variable

RPC/OpenOS/usr/lib/rpc.lua

@@ -66,6 +66,7 @@ function rpc.register(name,fn)
    if port == rpc.port then
     local rpcrq = serial.unserialize(data)
     if rpcf[rpcrq[1]] and isPermitted(from,rpcrq[1]) then
+     os.setenv("RPC_CLIENT", from)
      minitel.send(from,port,serial.serialize({rpcrq[2],pcall(rpcf[rpcrq[1]],table.unpack(rpcrq,3))}))
     elseif type(rpcrq[2]) == "string" then
      minitel.send(from,port,serial.serialize({rpcrq[2],false,"function unavailable"}))