adb: add `adb host-features`, report libusb status.
Add a 'host-features' command to get the features of the currently
running host adb server. Abuse it to report libusb status.
Bug: http://b/34983123
Test: adb host-features; adb kill-server; ADB_LIBUSB=1 adb start-server; adb host-features
Change-Id: I0e8d503a2dbdff9002ebb6ce8a298498a9421422
diff --git a/adb/transport.h b/adb/transport.h
index 3306388..490e513 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -47,6 +47,8 @@
// The 'cmd' command is available
extern const char* const kFeatureCmd;
extern const char* const kFeatureStat2;
+// The server is running with libusb enabled.
+extern const char* const kFeatureLibusb;
class atransport {
public: