The HAVE_DIRENT_H and PHP_WIN32 define blocks are reversed in php_scandir.h, included below.  As shown, GCC compilation will fail at line 15, blocking the compilation of php_scandir.c.  This is because HAVE_DIRENT_H is not defined at the shown line 3, therefore dirent.h does not include.  It is the php_config.h include which contains the HAVE_DIRENT_H define.

#include <sys/types.h>

#ifdef HAVE_DIRENT_H
#include <dirent.h>
#endif

#ifdef PHP_WIN32
#include "config.w32.h"
#include "win32/readdir.h"
#else
#include "php_config.h"
#endif

#ifndef HAVE_ALPHASORT
int alphasort(const struct dirent **a, const struct dirent **b);
#endif

#ifndef HAVE_SCANDIR
int scandir(const char *dirname,
	    struct dirent **namelist[],
	    int (*selector)(const struct dirent *entry),
	    int (*compare)(const struct dirent **a,const struct dirent **b) );
#endif