[mmp] Add unusual checks necessary to process obfuscated code. Fixes #53420. (#2117)

https://bugzilla.xamarin.com/show_bug.cgi?id=53420

tools/common/Assembly.cs

@@ -335,6 +335,9 @@ namespace Xamarin.Bundler {
 				
 				foreach (var mr in m.ModuleReferences) {
 					string name = mr.Name;
+					if (string.IsNullOrEmpty (name))
+						continue; // obfuscated assemblies.
+					
 					string file = Path.GetFileNameWithoutExtension (name);
 
 					switch (file) {

tools/linker/MonoTouch.Tuner/ListExportedSymbols.cs

@@ -76,7 +76,7 @@ namespace MonoTouch.Tuner
 
 		void ProcessMethod (MethodDefinition method)
 		{
-			if (method.IsPInvokeImpl && method.HasPInvokeInfo) {
+			if (method.IsPInvokeImpl && method.HasPInvokeInfo && method.PInvokeInfo != null) {
 				var pinfo = method.PInvokeInfo;
 				if (pinfo.Module.Name == "__Internal")
 					DerivedLinkContext.GetRequiredSymbolList (pinfo.EntryPoint).Add (method);