Ignore ro.adb.secure in user builds.

Require authorization by default, and remove the ability to override
that in user builds. (userdebug and eng are still free to do whatever
they want.)

Bug: http://b/21862859
Change-Id: Ibf8af375be5bf1141c1ad481eee7a59fb10a7adb
diff --git a/adb/adb.cpp b/adb/adb.cpp
index 9af1586..6a0540c 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -431,9 +431,9 @@
 
         parse_banner(reinterpret_cast<const char*>(p->data), t);
 
-        if (HOST || !auth_enabled) {
+        if (HOST || !auth_required) {
             handle_online(t);
-            if(!HOST) send_connect(t);
+            if (!HOST) send_connect(t);
         } else {
             send_auth_request(t);
         }