[generator] bring back static methods in the public API.

We were marking interface methods too much as non-public. Static methods
in the interfaces are generated in C# classes and they should remain public!

Author: atsushieno

tools/generator/CodeGenerator.cs

@@ -1100,7 +1100,7 @@ public void WriteMethod (Method method, TextWriter writer, string indent, CodeGe
 			writer.WriteLine ("{0}[Register (\"{1}\", \"{2}\", \"{3}\"{4})]",
 				indent, method.JavaName, method.JniSignature, method.IsVirtual ? method.ConnectorName : String.Empty, method.AdditionalAttributeString ());
 			WriteMethodCustomAttributes (method, writer, indent);
-			string visibility = type.IsInterface ? string.Empty : method.Visibility;
+			string visibility = type.IsInterface && !method.IsStatic ? string.Empty : method.Visibility;
 			writer.WriteLine ("{0}{1}{2}{3}{4} unsafe {5} {6}{7} ({8})",
 			                  indent,
 			                  visibility,

tools/generator/GenBase.cs

@@ -795,7 +795,7 @@ protected virtual bool GetEnumMappedMemberInfo ()
 
 		public void FixupMethodOverrides (CodeGenerationOptions opt)
 		{
-			foreach (Method m in methods.Where (m => !m.IsInterfaceDefaultMethod)) {
+			foreach (Method m in methods.Where (m => !m.IsStatic && !m.IsInterfaceDefaultMethod)) {
 				for (var bt = this.GetBaseGen (opt); bt != null; bt = bt.GetBaseGen (opt)) {
 					var bm = bt.Methods.FirstOrDefault (mm => mm.Name == m.Name && mm.Visibility == m.Visibility && ParameterList.Equals (mm.Parameters, m.Parameters));
 					if (bm != null && bm.RetVal.FullName == m.RetVal.FullName) { // if return type is different, it could be still "new", not "override".