Build adb if it's not available if users wants autoconnect.

Bug: 117584452
Test: m clean && m acloud && acloud create
Change-Id: I07d7927f69e3b18e51f9ffec6fa072c08a46a5e4
diff --git a/internal/constants.py b/internal/constants.py
index 80d22d0..88cbe33 100755
--- a/internal/constants.py
+++ b/internal/constants.py
@@ -99,3 +99,6 @@
 ENV_ANDROID_BUILD_TOP = "ANDROID_BUILD_TOP"
 
 LOCALHOST_ADB_SERIAL = "127.0.0.1:%d"
+
+SSH_BIN = "ssh"
+ADB_BIN = "adb"