adb: move all cleanup to a function with defined ordering.

We want to explicitly define the order in which we teardown adb, so
move all of the at_quick_exits sprinkled throughout into one function
containing all of the cleanup functions.

Bug: http://b/37104408
Test: adb kill-server; adb start-server
Change-Id: I394f5782eb147e394d4b87df1ba364c061de4b90
diff --git a/adb/transport.h b/adb/transport.h
index e129355..006aaf4 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -207,6 +207,7 @@
 std::string list_transports(bool long_listing);
 atransport* find_transport(const char* serial);
 void kick_all_tcp_devices();
+void kick_all_transports();
 
 void register_usb_transport(usb_handle* h, const char* serial,
                             const char* devpath, unsigned writeable);