remove mode_t from headers

it seems to fail with MSVC.

int works fine, and is what g_open() uses.

libvips/include/vips/memory.h

@@ -73,7 +73,7 @@ size_t vips_tracked_get_mem( void );
 size_t vips_tracked_get_mem_highwater( void );
 int vips_tracked_get_allocs( void );
 
-int vips_tracked_open( const char *pathname, int flags, mode_t mode );
+int vips_tracked_open( const char *pathname, int flags, int mode );
 int vips_tracked_close( int fd );
 int vips_tracked_get_files( void );
 

libvips/include/vips/util.h

@@ -254,7 +254,7 @@ int vips_filename_suffix_match( const char *path, const char *suffixes[] );
 gint64 vips_file_length( int fd );
 int vips__write( int fd, const void *buf, size_t count );
 
-int vips__open( const char *filename, int flags, mode_t mode );
+int vips__open( const char *filename, int flags, int mode );
 int vips__open_read( const char *filename );
 FILE *vips__fopen( const char *filename, const char *mode );
 

libvips/iofuncs/memory.c

@@ -356,7 +356,7 @@ vips_tracked_malloc( size_t size )
  * Returns: a file descriptor, or -1 on error.
  */
 int
-vips_tracked_open( const char *pathname, int flags, mode_t mode )
+vips_tracked_open( const char *pathname, int flags, int mode )
 {
 	int fd;
 

libvips/iofuncs/util.c

@@ -624,7 +624,7 @@ vips__set_create_time( int fd )
 /* open() with a utf8 filename, setting errno.
  */
 int
-vips__open( const char *filename, int flags, mode_t mode )
+vips__open( const char *filename, int flags, int mode )
 {
 	int fd;