fuse: Ignore extra options parameter on macOS

macOS macfuse has an extra options parameter for the setxattr and
getxattr FUSE callbacks.  The possible options are documented below.
However the underlying libguestfs APIs don't allow us to act on these
flags, so we ignore them for now.

(from https://manp.gs/mac/2/setxattr)

  XATTR_NOFOLLOW
    do not follow symbolic links. setxattr() normally sets attributes
    on the target of path if it is a symbolic link. With this option,
    setxattr() will act on the link itself.
  XATTR_NOFOLLOW_ANY
    do not follow any symbolic links encountered during pathname
    resolution. An error is returned if a symlink is encountered
    before the last component of path.
  XATTR_CREATE
    fail if the named attribute already exists.
  XATTR_REPLACE
    fail if the named attribute does not exist. Failure to specify
    XATTR_REPLACE or XATTR_CREATE allows creation and replacement.

Reported-by: Mohamed Akram
Fixes: https://github.com/libguestfs/libguestfs/issues/180
Related: https://github.com/macfuse/macfuse/issues/1065

lib/fuse.c

@@ -753,7 +753,11 @@ mount_local_fsync (const char *path, int isdatasync,
 
 static int
 mount_local_setxattr (const char *path, const char *name, const char *value,
-		      size_t size, int flags)
+		      size_t size, int flags
+#ifdef __APPLE__
+                      , uint32_t extra_apple_options_ignored
+#endif
+                      )
 {
   int r;
   DECL_G ();
@@ -777,7 +781,11 @@ mount_local_setxattr (const char *path, const char *name, const char *value,
  */
 static int
 mount_local_getxattr (const char *path, const char *name, char *value,
-                      size_t size)
+                      size_t size
+#ifdef __APPLE__
+                      , uint32_t extra_apple_options_ignored
+#endif
+                      )
 {
   const struct guestfs_xattr_list *xattrs;
   int free_attrs = 0;