Fixed SetMethodParameterUsage to use complete class declarations.

src/Generator/Library.cs

@@ -257,16 +257,14 @@ namespace CppSharp
             if (parameterIndex <= 0 )
                  throw new ArgumentException("parameterIndex");
 
-            foreach (var @class in context.FindClass(className))
-            {
-                var method = @class.Methods.Find(m => m.Name == methodName);
-                if (method == null)
-                    throw new ArgumentException("methodName");
-                if (method.Parameters.Count < parameterIndex)
-                    throw new ArgumentException("parameterIndex");
+            var @class = context.FindCompleteClass(className);
+            var method = @class.Methods.Find(m => m.Name == methodName);
+            if (method == null)
+                throw new ArgumentException("methodName");
+            if (method.Parameters.Count < parameterIndex)
+                throw new ArgumentException("parameterIndex");
 
-                method.Parameters[parameterIndex - 1].Usage = usage;
-            }
+            method.Parameters[parameterIndex - 1].Usage = usage;
         }
 
         public static void CopyClassFields(this ASTContext context, string source,