adb: fix leak of framework_fd.

Move the fdevent for the framework authentication connection out of
atransport into its own static variable in adb_auth_client, since its
lifetime is completely unrelated to that of the USB connection.

Bug: http://b/27297963
Change-Id: Ie6180d0b59d133120c5755e239e76ab33ed3cc1d
3 files changed