appop: protect mediaserver with OP_RECORD_AUDIO op check.

Some apps could use a binder to direct link to the mediaserver, bypassing
the android media framework security. Add an internal check to createTrack and openRecord
mediaserver's methods to protect them from undesired access.

Thanks to Blackphone for discovery and contribute this patch.

Change-Id: I12601d19ee093cf4c76ebf3a96aa63f6562dafac
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>