Add bitness info to <transport>.

Only valid for transport == passthrough or toggled.
Example:
<transport>hwbinder</transport>
<transport arch="64">passthrough</transport>
<transport arch="32+64">passthrough</transport>
<transport arch="32">passthrough</transport>

Allow transport tag to be missing (for native HALs like GLES).

Bug: 35966597
Test: libvintf_test
Change-Id: I80928a5d46f3097ed18f2894e46762127b29bd4c
diff --git a/TransportArch.cpp b/TransportArch.cpp
new file mode 100644
index 0000000..de8dd59
--- /dev/null
+++ b/TransportArch.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+#include "TransportArch.h"
+
+namespace android {
+namespace vintf {
+
+bool TransportArch::empty() const {
+    return transport == Transport::EMPTY && arch == Arch::ARCH_EMPTY;
+}
+
+bool TransportArch::isValid() const {
+    switch (transport) {
+        case Transport::EMPTY: // fallthrough
+        case Transport::HWBINDER:
+            return arch == Arch::ARCH_EMPTY;
+
+        case Transport::PASSTHROUGH:
+            return arch != Arch::ARCH_EMPTY;
+
+        case Transport::TOGGLED:
+            return true; // allow all arch for toggled
+    }
+}
+
+} // namespace vintf
+} // namespace android