AAPT2: Add Manifest fixing/validation

Change-Id: I7f6d8b74d1c590adc356b4da55cb6cb777cdf1da
diff --git a/tools/aapt2/XmlDom.h b/tools/aapt2/XmlDom.h
index b1987f1..9a46bcb 100644
--- a/tools/aapt2/XmlDom.h
+++ b/tools/aapt2/XmlDom.h
@@ -34,6 +34,8 @@
 namespace aapt {
 namespace xml {
 
+constexpr const char16_t* kSchemaAndroid = u"http://schemas.android.com/apk/res/android";
+
 struct RawVisitor;
 
 /**