Removing redundant shebang line check

Hi, The proposed patch removes code that implemented shebang line support (#! /usr/bin/php). Starting with PHP-5.3 it is handled by scanner, and we don't need to check it twice. With this check removed, it's become possible to eliminate the open() syscall (and also several fstat() and mmap() calls) for the requested file with opcode caches. The patch does it by replacing VCWD_FOPEN() in php_fopen_primary_script() by zend_open_stream() which call for callback that can be overridden by opcode cache. I like to commit it into HEAD and PHP_5_3 on weekend. I hope nobody have objections. Thanks. Dmitry.