access.2, chmod.2, chown.2, link.2, mkdir.2, open.2, readlink.2, rename.2, stat.2...

access.2, chmod.2, chown.2, link.2, mkdir.2, open.2, readlink.2, rename.2, stat.2, symlink.2, unlink.2, mkfifo.3, scandir.3: Minor fix: remove section numbers in references to functions inside page

With the page merges, we now have some references to functions
within the page that have section numbers. Remove those.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>