Don't throw script errors when ordered before udev

Due to the way libdnf/libsolv resolves RPM installation order, it is
possible that this package will be installed before systemd-udev is
installed. If that happens, /sbin/udevadm is unavailable and an error
is thrown. However, it's safe to skip the call to /sbin/udevadm if
systemd-udev is not available yet. When that package is installed,
it runs the necessary actions itself.

Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>

rdma-core.spec

@@ -1,6 +1,6 @@
 Name: rdma-core
 Version: 30.0
-Release: 3%{?dist}
+Release: 4%{?dist}
 Summary: RDMA core userspace libraries and daemons
 
 # Almost everything is licensed under the OFA dual GPLv2, 2 Clause BSD license
@@ -356,9 +356,11 @@ rm -f %{buildroot}/%{_sbindir}/srp_daemon.sh
 %ldconfig_scriptlets -n librdmacm
 
 %post -n rdma-core
+if [ -x /sbin/udevadm ]; then
 /sbin/udevadm trigger --subsystem-match=infiniband --action=change || true
 /sbin/udevadm trigger --subsystem-match=net --action=change || true
 /sbin/udevadm trigger --subsystem-match=infiniband_mad --action=change || true
+fi
 
 %post -n ibacm
 %systemd_post ibacm.service
@@ -660,6 +662,9 @@ rm -f %{buildroot}/%{_sbindir}/srp_daemon.sh
 %endif
 
 %changelog
+* Thu Jul 02 2020 Stephen Gallagher <sgallagh@redhat.com> - 30.0-4
+- Don't throw script errors if udev is not installed
+
 * Wed Jul  1 2020 Jeff Law <law@redhat.com> - 30.0-3
 - Disable LTO