This parameter allows the user to choose which storage backend / stevedore
that the H/2 receive buffers are allocated from. By default it uses
Transient.

Conflicts:
	bin/varnishd/mgt/mgt.h
	bin/varnishd/mgt/mgt_param.h
	bin/varnishd/mgt/mgt_param_tbl.c
	include/tbl/params.h