setup-environment: Add sdl PACKAGECONFIG for qemu-native.

* Add PACKAGECONFIG for qemu-native for qemu machines. Get the machine
  name and added when its one of the qemu machine.

* SB-3879

Signed-off-by: Noor Ahsan <noor_ahsan@mentor.com>
Merge pull request #365 from Noor-Ahsan/alsa-utils

setup-environment: Add sdl PACKAGECONFIG for qemu-native.