Updated Build.PL to handle release tests as part of disttest.

Build.PL

@@ -1,9 +1,40 @@
 use 5.006;
 use strict;
 use warnings;
+
 use Module::Build;
 
-my $builder = Module::Build->new(
+
+my $class = Module::Build->subclass(
+	code =>
+	q|
+		# Override 'test' to support running extended tests in the xt/
+		# directory.
+		sub ACTION_test
+		{
+			my ( $self ) = @_;
+			
+			$self->recursive_test_files(1);
+			
+			$self->test_files( 't', 'xt' )
+				if $ENV{'RELEASE_TESTING'};
+			
+			return $self->SUPER::ACTION_test();
+		}
+		
+		# Force running extended tests when testing the distribution.
+		sub ACTION_disttest
+		{
+			my ( $self ) = @_;
+			
+			local $ENV{ RELEASE_TESTING } = 1;
+			
+			return $self->SUPER::ACTION_disttest();
+		}
+	|,
+);
+
+my $builder = $class->new(
 	module_name         => 'IPC::Concurrency::DBI',
 	license             => 'GPL_3',
 	dist_author         => q{Guillaume Aubert <aubertg@cpan.org>},