AAPT2: Add Inline Complex XML support

See: https://developer.android.com/guide/topics/resources/complex-xml-resources.html

Change-Id: I8274c85e25cabf90423141c228697e873167d136
diff --git a/tools/aapt2/xml/XmlUtil.h b/tools/aapt2/xml/XmlUtil.h
index b75d8ac..a6ad79d 100644
--- a/tools/aapt2/xml/XmlUtil.h
+++ b/tools/aapt2/xml/XmlUtil.h
@@ -30,6 +30,7 @@
 constexpr const char* kSchemaPrivatePrefix = "http://schemas.android.com/apk/prv/res/";
 constexpr const char* kSchemaAndroid = "http://schemas.android.com/apk/res/android";
 constexpr const char* kSchemaTools = "http://schemas.android.com/tools";
+constexpr const char* kSchemaAapt = "http://schemas.android.com/aapt";
 
 /**
  * Result of extracting a package name from a namespace URI declaration.
@@ -62,8 +63,12 @@
  * Returns an XML Android namespace for the given package of the form:
  *
  * http://schemas.android.com/apk/res/<package>
+ *
+ * If privateReference == true, the package will be of the form:
+ *
+ * http://schemas.android.com/apk/prv/res/<package>
  */
-std::string buildPackageNamespace(const StringPiece& package);
+std::string buildPackageNamespace(const StringPiece& package, bool privateReference=false);
 
 /**
  * Interface representing a stack of XML namespace declarations. When looking up the package