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

1 files changed, 1 insertions, 1 deletions

diff --git a/adb.h b/adb.h
index a30e2978..aea5fb86 100644
--- a/adb.h
+++ b/adb.h
@@ -54,7 +54,7 @@ constexpr size_t LINUX_MAX_SOCKET_SIZE = 4194304;
 std::string adb_version();
 
 // Increment this when we want to force users to start a new adb server.
-#define ADB_SERVER_VERSION 38
+#define ADB_SERVER_VERSION 39
 
 class atransport;