Add permission checking for binder IPC.

Change-Id: Ia224e29427d39a6eeb0800a65ad2a8df2e91bebc
Do not apply permission checks to private files.

Change-Id: I472d9630de5113667c289dce7e4fdc8eace04e36
Fix security_binder_transfer_binder hook.

Drop the owning task argument to security_binder_transfer_binder
since ref->node->proc can be NULL (dead owner?).
Revise the SELinux checking to apply a single transfer check between
the source and destination tasks.  Owning task is no longer relevant.
Drop the receive permission definition as it is no longer used.

This makes the transfer permission similar to the call permission; it is only
useful if you want to allow a binder IPC between two tasks (call permission)
but deny passing of binder references between them (transfer permission).

Change-Id: I6ec460ede8e07dadc9f52b61534b2b0021617302