android: binder: support for file-descriptor arrays.

This patch introduces a new binder_fd_array object,
that allows us to support one or more file descriptors
embedded in a buffer that is scatter-gathered.

Change-Id: I273d7e00807eda4defc5c94c4bd86e4812e2c7a8
Signed-off-by: Martijn Coenen <maco@google.com>
Git-commit: 5b3e1767
Git-repo: https://git.linaro.org/kernel/linux-linaro-stable


Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>