Android: Process events from the JVM (#1326)

Used to keep track of broadcast events on the main lua loop.

It is a generic mechanism able to execute chunks of lua code triggered by code running inside the JVM.

ffi/input_android.lua

@@ -198,6 +198,14 @@ function input.waitForEvent(sec, usec)
                         android.lib.AInputQueue_finishEvent(android.app.inputQueue, event[0], handled)
                     end
                 end
+            elseif poll_state == C.LOOPER_ID_USER then
+                local message = ffi.new("unsigned char [4]")
+                C.read(fd[0], message, 4)
+                if message[0] == C.AEVENT_POWER_CONNECTED then
+                    commandHandler(C.AEVENT_POWER_CONNECTED, 0)
+                elseif message[0] == C.AEVENT_POWER_DISCONNECTED then
+                    commandHandler(C.AEVENT_POWER_DISCONNECTED, 0)
+                end
             end
             if android.app.destroyRequested ~= 0 then
                 android.LOGI("Engine thread destroy requested!")