05core: skip sysroot.mount for remote kdump

If kdump is setup to upload logs to a remote host, the
XFS module may not be loaded, which cause sysroot.mount to fail.

If the target for logs is SSH, kdump will boot with a `kdump_remote_ip`
karg. Skip generating sysroot.mount in that case so kdump can boot
without having to load XFS.

This is a temporary fix until we migrate older systems to have a root
karg: coreos/fedora-coreos-tracker#1675

See https://issues.redhat.com/browse/OCPBUGS-27935

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-ignition/coreos-diskful-generator

@@ -66,7 +66,11 @@ mkdir -p ${UNIT_DIR}
 # We want to generate sysroot.mount on ostree systems, but we don't want
 # to run if there's already a root= karg, where the systemd-fstab-generator
 # should win.
-if test -n "$(cmdline_arg ostree)" && test -z "$(cmdline_arg root)"; then
+# We also don't want to generate sysroot.mount if we are booting a kdump kernel
+# that aims to upload logs to a remote target, as the XFS kernel module won't be loaded
+# https://issues.redhat.com/browse/OCPBUGS-27935
+# FIXME: this kdump case should be removed when we are done with https://github.com/coreos/fedora-coreos-tracker/issues/1675
+if test -n "$(cmdline_arg ostree)" && test -z "$(cmdline_arg root)" && test -z "$(cmdline_arg kdump_remote_ip)"; then
     cat >${UNIT_DIR}/sysroot.mount << 'EOF'
 [Unit]
 Before=initrd-root-fs.target