Fix TAP tests with Perl 5.12

Perl 5.12 ships with a somewhat broken version of Test::Simple, so skip
the tests if that is found.

The relevant fix is

    0.98  Wed, 23 Feb 2011 14:38:02 +1100
        Bug Fixes
        * subtest() should not fail if $? is non-zero. (Aaron Crane)

src/test/perl/TestLib.pm

@@ -44,6 +44,14 @@ BEGIN
 	{
 		plan skip_all => "version of Test::More is too old to support subplans";
 	};
+
+	eval {
+		require Test::Simple;
+		Test::Simple->VERSION('0.98');
+	} or do
+	{
+		plan skip_all => "version of Test::Simple is too old to support subplans properly";
+	};
 }
 
 # Set to untranslated messages, to be able to compare program output