meson: do no build upower on macos

this is just causing errors and nothing usefull, upower is not available
on macos.

Reviewed-by: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Differential Revision: https://phab.enlightenment.org/D11652

src/modules/ecore/meson.build

@@ -1,5 +1,5 @@
 
-if sys_windows == false
+if sys_windows == false and sys_osx == false
 
   system_modules = [
     'systemd',