tools/misc: Remove obsolete xen-bugtool

tools/misc: Remove obsolete xen-bugtool

xen-bugtool relies on code that has been removed in commit 9e8672f1c3
"tools: remove xend and associated python modules", more than 5 years
ago. Remove it, since it confuses users.

    -$ /usr/sbin/xen-bugtool
    Traceback (most recent call last):
      File "/usr/sbin/xen-bugtool", line 9, in <module>
	from xen.util import bugtool
    ImportError: No module named xen.util

Signed-off-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=866380
Acked-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>