Support ARM Linux device and add Beaglebone as a support device

This patch set enables building PPSSPP on an embedded Linux board called the Beaglebone/Beaglebone Black. Minor tweaks are made to easily support thiis board.
@Sonicadvance1 made a good point on IRC.  Does this device have /dev/shm?

We probably ought to use /dev/shm where available and writable.

-[Unknown]