adb: add adb_get_feature_set.

Extract a feature set getter function from commandline.cpp.

Change-Id: I30a3eb0b060a88379e29be16264637816e378978
diff --git a/adb/adb_client.h b/adb/adb_client.h
index 5de0638..112c13a 100644
--- a/adb/adb_client.h
+++ b/adb/adb_client.h
@@ -18,6 +18,7 @@
 #define _ADB_CLIENT_H_
 
 #include "adb.h"
+#include "transport.h"
 
 #include <string>
 
@@ -52,4 +53,10 @@
 // event of OKAY, false in the event of FAIL or protocol error.
 bool adb_status(int fd, std::string* error);
 
+// Create a host command corresponding to selected transport type/serial.
+std::string format_host_command(const char* command, TransportType type, const char* serial);
+
+// Get the feature set of the current preferred transport.
+bool adb_get_feature_set(FeatureSet* feature_set, std::string* error);
+
 #endif