PHP event extractor too strict on doc blocks

Since we are allowing a single space before the * on doc blocks,
the php event extractor should be able to find events in such situations aswell.

Currently it fails with:

phpbb_event_export_php_test::test_crawl_php_file with data set #18 ('includes/mcp/mcp_ban.php')
LogicException: Can not find @var lines for event 'core.mcp_ban_main' in file 'includes/mcp/mcp_ban.php:55'