Pull up following revision(s) (requested by riastradh in ticket #946):

sys/dev/sysmon/sysmon_envsys.c: revision 1.145

Don't queue sysmon refresh until the rndsource is attached.

Using the rndsource, as refreshing the sensors will do, is not
allowed until _after_ rnd_source_attach.

XXX pullup-7
XXX pullup-8
XXX pullup-9

(martin)