define PACKED_STRUCT_UNALIGNED correctly

Defining PACKED_STRUCT_UNALIGNED to a noop in ruby/config.h (via
`configure') prevents the definition in include/ruby/defines.h
from working

This should have been fixed in r46914, so there's a size
regression for some objects since Ruby 2.2+.  I do not believe
we can backport to existing releases, either, since it can
affect ABI.

Add a test for Time objects on common x86-based platforms to
check for future regressions.

* configure.in: remove PACKED_STRUCT_UNALIGNED definition
* test/ruby/test_time.rb (test_memsize): new test for x86

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58442 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -1642,13 +1642,11 @@ AC_CACHE_CHECK(packed struct attribute, rb_cv_packed_struct,
 			PACKED_STRUCT(struct { int a; });], [],
 		[rb_cv_packed_struct=$mac; break])
     done])
-packed_struct_unaligned=x
 if test "$rb_cv_packed_struct" != no; then
     AC_DEFINE_UNQUOTED([PACKED_STRUCT(x)], [$rb_cv_packed_struct])
 else
     AC_DEFINE_UNQUOTED([PACKED_STRUCT(x)], x)
 fi
-AC_DEFINE_UNQUOTED(PACKED_STRUCT_UNALIGNED(x), $packed_struct_unaligned)
 
 AC_DEFUN([RUBY_CHECK_PRINTF_PREFIX], [
 AC_CACHE_CHECK([for printf prefix for $1], [rb_cv_pri_prefix_]AS_TR_SH($1),[

test/ruby/test_time.rb

@@ -1110,4 +1110,21 @@ class TestTime < Test::Unit::TestCase
     end.new
     assert_raise_with_message(TypeError, /Inexact/) {Time.at(x)}
   end
+
+  def test_memsize
+    # Time objects are common in some code, try to keep them small
+    skip "Time object size test" if /^(?:i.?86|x86_64)-linux/ !~ RUBY_PLATFORM
+    require 'objspace'
+    t = Time.at(0)
+    size = GC::INTERNAL_CONSTANTS[:RVALUE_SIZE]
+    case size
+    when 20 then expect = 50
+    when 40 then expect = 86
+    else
+      flunk "Unsupported RVALUE_SIZE=#{size}, update test_memsize"
+    end
+    assert_equal expect, ObjectSpace.memsize_of(t)
+  rescue LoadError => e
+    skip "failed to load objspace: #{e.message}"
+  end
 end