audioflinger: Make use of android-base/macros.h

Replace local definitions of "array size" macro, and
declarations of non-copyable objects with corresponding
constructs from android-base/macros.h.

Also change "protected:" to "private:" for classes
not designed to be inherited.

Change-Id: I2d1e6d153511ed84d52fe6377879f83258890653
Test: make