Move adbd's legacy USB implementation to fastboot.

This code path is effectively dead in adbd, and fastboot's dependency on
libadbd makes it hard to refactor adbd's dependencies.

Bug: http://b/150317254
Test: built and flashed aosp_walleye-eng
Change-Id: I5118136d32fdcbbd011559ed0a4a71e1dc7bf064
Merged-In: I5118136d32fdcbbd011559ed0a4a71e1dc7bf064
(cherry picked from commit 0871824de6c5b868f2a2e67c9b5673cb2181b4c6)
21 files changed