specfile: use _datadir as var expansion not exec

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Steven Dake <sdake@redhat.com>

corosync.spec.in

@@ -139,7 +139,7 @@ fi
 %{_sysconfdir}/dbus-1/system.d/corosync-signals.conf
 %endif
 %if %{with snmp}
-%(_datadir)/snmp/mibs/COROSYNC-MIB.txt
+%{_datadir}/snmp/mibs/COROSYNC-MIB.txt
 %endif
 %{_initrddir}/corosync
 %{_initrddir}/corosync-notifyd