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.cpp b/adb/transport.cpp
index 60f3b5c..c951f5b 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -51,6 +51,7 @@
const char* const kFeatureShell2 = "shell_v2";
const char* const kFeatureCmd = "cmd";
const char* const kFeatureStat2 = "stat_v2";
+const char* const kFeatureLibusb = "libusb";
static std::string dump_packet(const char* name, const char* func, apacket* p) {
unsigned command = p->msg.command;