Add namespace handling in attribute values

Previously, you could only reference namespace prefixes in attribute names:

<View xmlns:appcompat="http://schemas.android.com/apk/res/android.support.v7.appcompat"
      appcompat:name="hey"
      ...

Now you can also reference them in resource names within an attribute value:

      ...
      android:text="@appcompat:string/confirm"
      ...

Which will be treated as "@android.support.v7.appcompat:string/confirm".

Change-Id: Ib076e867a990c80cf877a704eb77cd1ef0b23b52
diff --git a/tools/aapt2/Flag.cpp b/tools/aapt2/Flag.cpp
index 3b2ff51..0f63c2c 100644
--- a/tools/aapt2/Flag.cpp
+++ b/tools/aapt2/Flag.cpp
@@ -65,7 +65,7 @@
     for (int i = 0; i < argc; i++) {
         const StringPiece arg(argv[i]);
         if (*arg.data() != '-') {
-            sArgs.emplace_back(arg.toString());
+            sArgs.push_back(arg.toString());
             continue;
         }