Implement AAPT Bundle format

AAPT will scan XML files looking for the <aapt:attr> XML tag.

<!-- @layout/bundle.xml -->
<ImageView xmlns:aapt="http://schemas.android.com/aapt">
  <aapt:attr name="android:src">
    <vector android:pathData="..." ...>
    </vector>
  </aapt:attr>
</ImageView>

The SINGLE child element of the <aapt:attr> tag is extracted into its own top
level resource. It is given a generated name.

The parent element of <aapt:attr> is then given the resource attribute that was assigned
to the `name' attribute. The value is set to a reference to the generated resource.

<!-- @layout/bundle.xml -->
<ImageView android:src="@drawable/bundle_1.xml">
</ImageView>

<!-- @layout/bundle_1.xml -->
<vector android:pathData="..." ...>
</vector>

Bug:22627686
Change-Id: I31bc96aae30d38bfd0b16508d0f585de5fd88a07

tools/aapt/Resource.cpp

@@ -1537,7 +1537,14 @@ status_t buildResources(Bundle* bundle, const sp<AaptAssets>& assets, sp<ApkBuil
     std::queue<CompileResourceWorkItem>& workQueue = table.getWorkQueue();
     while (!workQueue.empty()) {
         CompileResourceWorkItem& workItem = workQueue.front();
-        err = compileXmlFile(bundle, assets, workItem.resourceName, workItem.file, &table, xmlFlags);
+        if (workItem.xmlRoot != NULL) {
+            err = compileXmlFile(bundle, assets, workItem.resourceName, workItem.xmlRoot,
+                                 workItem.file, &table, xmlFlags);
+        } else {
+            err = compileXmlFile(bundle, assets, workItem.resourceName, workItem.file,
+                                 &table, xmlFlags);
+        }
+
         if (err == NO_ERROR) {
             assets->addResource(workItem.resPath.getPathLeaf(),
                     workItem.resPath,