Allow Bluetooth HAL CAP_SYS_NICE

The Bluetooth HAL has threads that process Bluetooth audio.  They need
to be scheduled as RT priority, so allow the Bluetooth HAL to set its
threads to RT scheduling.

Bug 37518404
Test:  play Bluetooth audio, confirm priority via systrace
Change-Id: I4928cf182a0805c0714e4d073cba15c864fbe328
1 file changed