Revert "lxc_fuse: Tell FUSE that /proc/meminfo is nonseekable"

Revert "lxc_fuse: Tell FUSE that /proc/meminfo is nonseekable"

After v8.1.0-61-g030faee28d it is no longer necessary to make the
/proc/meminfo file nonseekable as our code that fills the file
with spoofed values can handle seeking just fine.

Previously, `free(1)` was okay with failed lseek(), but this was
ages ago and meanwhile the procps project moved to creating a
library and moved the file parsing code under an exported
function. In attempt to make the function callable multiple
times, it can lseek() multiple times and failure to do so is
fatal.

This reverts commit 766495508650bebd5f4ac23224ecd0a2ee2ca9eb

Resolves: https://gitlab.com/libvirt/libvirt/-/issues/492
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>