hyperv: Introduce and export 'facility' variable.

hyperv: Introduce and export 'facility' variable.

In its upstream commit [1] openwsman dropped 'facility' variable
which is documented as:

 * all processes that use the libu must define a "facility" variable somewhere
 * to satisfy this external linkage reference.
 *
 * Such variable will be used as the syslog(3) facility argument.

Well, prior to that commit, openwsman itself declared the
variable (and set it to LOG_DAEMON). Now it's up to us.

Yeah, the variable naming is terrible and also I we are not using
libu directly, but apparently libwsman.so requires it anyway:

  $ objdump -T /usr/lib64/libwsman.so | grep facility
  0000000000000000      D  *UND*  0000000000000000  Base        facility

1: https://github.com/Openwsman/openwsman/commit/d72c51f21b9c85a773b7955ac587d2d3cea982c1
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>