AAPT: Allow duplicate attribute definitions if identical

This allows libraries to coexist a bit easier, since a lot of them
declare the same attribute. When used together they cause errors.
Bug:27101533

Change-Id: I649cf17bc587c4814f849d5ac522daf74495adcf
diff --git a/tools/aapt/ResourceTable.h b/tools/aapt/ResourceTable.h
index 4b7b3cd..cf1e992 100644
--- a/tools/aapt/ResourceTable.h
+++ b/tools/aapt/ResourceTable.h
@@ -571,6 +571,18 @@
 
     void getDensityVaryingResources(KeyedVector<Symbol, Vector<SymbolDefinition> >& resources);
 
+    /**
+     * Make an attribute with the specified format. If another attribute with the same name but
+     * different format exists, this method returns false. If the name is not taken, or if the
+     * format is identical, this returns true.
+     */
+    bool makeAttribute(const String16& package,
+                       const String16& name,
+                       const SourcePos& source,
+                       int32_t format,
+                       const String16& comment,
+                       bool appendComment);
+
 private:
     void writePublicDefinitions(const String16& package, FILE* fp, bool pub);
     sp<Package> getPackage(const String16& package);