don't print anonymous struct class name

mrbgems/mruby-struct/mrblib/struct.rb

@@ -47,7 +47,12 @@ if Object.const_defined?(:Struct)
     end
 
     def _inspect
-      str = "#<struct #{self.class.to_s} "
+      name = self.class.to_s
+      if name[0] == "#"
+        str = "#<struct "
+      else
+        str = "#<struct #{name} "
+      end
       buf = []
       self.each_pair do |k,v|
         buf.push [k.to_s + "=" + v._inspect]

mrbgems/mruby-struct/test/struct.rb

@@ -103,7 +103,7 @@ end
 assert('struct inspect') do
   c = Struct.new(:m1, :m2, :m3, :m4, :m5)
   cc = c.new(1,2,3,4,5)
-  assert_equal "#<struct #{c.inspect} m1=1, m2=2, m3=3, m4=4, m5=5>", cc.inspect
+  assert_equal "#<struct m1=1, m2=2, m3=3, m4=4, m5=5>", cc.inspect
 end
 
 assert('Struct#length, Struct#size') do