tools include UAPI: Update linux/mount.h copy

To pick the changes from:

  dd8b477f

 ("mount: Support "nosymfollow" in new mount api")

That ends up adding support for the new MOUNT_ATTR_NOSYMFOLLOW mount
attribute:

  $ tools/perf/trace/beauty/fsmount.sh > before
  $ cp include/uapi/linux/mount.h tools/include/uapi/linux/mount.h
  $ tools/perf/trace/beauty/fsmount.sh > after
  $ diff -u before after
  --- before	2021-07-01 13:34:04.542517355 -0300
  +++ after	2021-07-01 13:34:12.423694537 -0300
  @@ -7,4 +7,5 @@
   	[ilog2(0x00000020) + 1] = "STRICTATIME",
   	[ilog2(0x00000080) + 1] = "NODIRATIME",
   	[ilog2(0x00100000) + 1] = "IDMAP",
  +	[ilog2(0x00200000) + 1] = "NOSYMFOLLOW",
   };
  $

So now one can use it in --filter expressions for tracepoints.

This silences this perf build warnings:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/mount.h' differs from latest version at 'include/uapi/linux/mount.h'
  diff -u tools/include/uapi/linux/mount.h include/uapi/linux/mount.h

Cc: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>