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.
Yes /dev/shm is available. Since /dev/shm uses memory. How large does this temp file typicallyt get?

 Looking at this a bit closer I don't understand why the default "/tmp/gc_mem.tmp" wouldn't work. The /tmp/ directory is also available on my system