[Xamarin.Android.Tools.ApiXmlAdjuster] Cleanup (#82)

Rename `reader` variable to `writer`, to match actual use/semantics.

Avoid recurring `<package>` element occurrence: when reading multiple
API XML files which contain the same `//package/@name` value, there
would be multiple `<package/>` elements in the resulting document.

It was almost harmless, but it could result in XPath
query differences.

Author: atsushieno

src/Xamarin.Android.Tools.ApiXmlAdjuster/JavaApiXmlGeneratorExtensions.cs

@@ -10,12 +10,12 @@ public static class JavaApiXmlGeneratorExtensions
 	{
 		public static void Save (this JavaApi api, string xmlfile)
 		{
-			using (var reader = XmlWriter.Create (xmlfile, new XmlWriterSettings () {
+			using (var writer = XmlWriter.Create (xmlfile, new XmlWriterSettings () {
 				Encoding = new UTF8Encoding (false, true),
 				Indent = true,
 				OmitXmlDeclaration = true,
 				}))
-				api.Save (reader);
+				api.Save (writer);
 		}
 
 		public static void Save (this JavaApi api, XmlWriter writer)

src/Xamarin.Android.Tools.ApiXmlAdjuster/JavaApiXmlLoaderExtensions.cs

@@ -31,9 +31,12 @@ public static void Load (this JavaApi api, XmlReader reader, bool isReferenceOnl
 						break; // </api>
 					if (reader.NodeType != XmlNodeType.Element || reader.LocalName != "package")
 						throw XmlUtil.UnexpectedElementOrContent ("api", reader, "package");
-					var pkg = api.Packages.FirstOrDefault (p => p.Name == reader.GetAttribute ("name")) ?? new JavaPackage (api);
+					var pkg = api.Packages.FirstOrDefault (p => p.Name == reader.GetAttribute ("name"));
+					if (pkg == null) {
+						pkg = new JavaPackage (api);
+						api.Packages.Add (pkg);
+					}
 					pkg.Load (reader, isReferenceOnly);
-					api.Packages.Add (pkg);
 				} while (true);
 
 				XmlUtil.VerifyEndElement (reader, "api");