build-sys: fix build when daemon is disabled by not installing libvirtd.8

Since the rule to build libvirtd.8 is within the WITH_LIBVIRTD conditional,
so declare the man page in there as well. Without this change, build
without daemon will fail.

daemon/Makefile.am

@@ -41,12 +41,12 @@ EXTRA_DIST =						\
 	$(AVAHI_SOURCES)				\
 	$(DAEMON_SOURCES)
 
-man_MANS = libvirtd.8
-
 BUILT_SOURCES =
 
 if WITH_LIBVIRTD
 
+man_MANS = libvirtd.8
+
 sbin_PROGRAMS = libvirtd
 
 confdir = $(sysconfdir)/libvirt/