Camera3: Avoid starting streams twice
Camera3: Avoid starting streams twice

 The start method of some streams
 (most notably the metadata) could be
 called twice. This scenario should be
 handled by returning immediatly and
 avoiding the initialization of new
 threads and resources.

This change is authored by Emilian Peev
<epeevs@codeaurora.org>

Bug: 18258028
Bug: 17912331
Change-Id: Ife6613bdca069bc63193802e0bb88273e63998f9

maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead