Drop memberless Data/Struct#inspect trailing space

Anonymous memberless Structs and Data were returning `#<struct >` and
`#<data >` with a trailing space. Now they return `#<struct>` and
`#<data>` to match attrless class behavior and look a bit more compact.

Author: havenwood

struct.c

@@ -981,6 +981,7 @@ inspect_struct(VALUE s, VALUE prefix, int recur)
     char first = RSTRING_PTR(cname)[0];
 
     if (recur || first != '#') {
+        rb_str_cat2(str, " ");
         rb_str_append(str, cname);
     }
     if (recur) {
@@ -997,7 +998,7 @@ inspect_struct(VALUE s, VALUE prefix, int recur)
         if (i > 0) {
             rb_str_cat2(str, ", ");
         }
-        else if (first != '#') {
+        else {
             rb_str_cat2(str, " ");
         }
         slot = RARRAY_AREF(members, i);
@@ -1031,7 +1032,7 @@ inspect_struct(VALUE s, VALUE prefix, int recur)
 static VALUE
 rb_struct_inspect(VALUE s)
 {
-    return rb_exec_recursive(inspect_struct, s, rb_str_new2("#<struct "));
+    return rb_exec_recursive(inspect_struct, s, rb_str_new2("#<struct"));
 }
 
 /*
@@ -1910,7 +1911,7 @@ rb_data_with(int argc, const VALUE *argv, VALUE self)
 static VALUE
 rb_data_inspect(VALUE s)
 {
-    return rb_exec_recursive(inspect_struct, s, rb_str_new2("#<data "));
+    return rb_exec_recursive(inspect_struct, s, rb_str_new2("#<data"));
 }
 
 /*

test/ruby/test_data.rb

@@ -259,7 +259,7 @@ def test_memberless
     assert_equal(klass.new, test)
     assert_not_equal(Data.define.new, test)
 
-    assert_equal('#<data >', test.inspect)
+    assert_equal('#<data>', test.inspect)
     assert_equal([], test.members)
     assert_equal({}, test.to_h)
     assert_predicate(test, :frozen?)