push @socketengines, 'poll' if test_header $compiler, 'poll.h';
push @socketengines, 'ports' if test_header $compiler, 'ports.h';
foreach my $socketengine (@socketengines) {
push @socketengines, 'poll' if test_header $compiler, 'poll.h';
push @socketengines, 'ports' if test_header $compiler, 'ports.h';
foreach my $socketengine (@socketengines) {