varnishtop: handle shm_reclen > 255
varnishtop: handle shm_reclen > 255

varnishtop used to have a hard-coded max record length of 255 bytes.
This broke with the change that allows larger record length.  Use a
dynamic buffer instead.

git-svn-id: 7d4b18ab7d176792635d6a7a77dd8cbbea8e8daa@4173 d4fa192b-c00b-0410-8231-f00ffab90ce4

wikimedia/operations-debs-varnish,CartoDB/Varnish-Cache,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,CartoDB/Varnish-Cache,ssm/pkg-varnish,CartoDB/Varnish-Cache,ssm/pkg-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish