Revert "linux-user: fix compat with glibc >= 2.36 sys/mount.h"

Revert "linux-user: fix compat with glibc >= 2.36 sys/mount.h"

This reverts commit 3cd3df2a9584e6f753bb62a0028bd67124ab5532.

glibc has fixed (in 2.36.9000-40-g774058d729) the problem
that caused a clash when both sys/mount.h annd linux/mount.h
are included, and backported this to the 2.36 stable release
too:

  https://sourceware.org/glibc/wiki/Release/2.36#Usage_of_.3Clinux.2Fmount.h.3E_and_.3Csys.2Fmount.h.3E

It is saner for QEMU to remove the workaround it applied for
glibc 2.36 and expect distros to ship the 2.36 maint release
with the fix. This avoids needing to add a further workaround
to QEMU to deal with the fact that linux/brtfs.h now also pulls
in linux/mount.h via linux/fs.h since Linux 6.1

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230110174901.2580297-3-berrange@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>