glocalfile: Use MAXSYMLINKS when following symlinks

Currently, readlink() is used only 12 times when expanding symlinks.
However, kernel uses 40 for this purpose and it is defined as MAXSYMLINKS.
Use that constant if available, or 40. See:
https://github.com/torvalds/linux/include/linux/namei.h.
9 jobs for 326-trash-symlinks-glib-2-58 in 27 minutes and 39 seconds (queued for 4 seconds)