Fix NPE in layer destruction
Fix NPE in layer destruction

 Bug: 13111945
 Fixes an issue where a layer is destroyed after the GLRenderer
 lost its Surface. Instead just check that the context we want is
 current regardless of the active surface

Change-Id: I6537e6232b5c667b218b896ed5ef390fbe956344

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base