Add check files for network and nfsroot

This way dracut will not try to install them if the system does not have
the needed prerequisites.

diff --git a/modules.d/40network/check b/modules.d/40network/check
new file mode 100755 (executable)
index 0000000..77d876b
--- /dev/null
+++ b/modules.d/40network/check
@@ -0,0 +1,3 @@
+#!/bin/sh
+which ip dhclient hostname >/dev/null 2>&1 || exit 1
+exit 0
\ No newline at end of file

diff --git a/modules.d/40nfsroot/check b/modules.d/40nfsroot/check
new file mode 100755 (executable)
index 0000000..e0cecb8
--- /dev/null
+++ b/modules.d/40nfsroot/check
@@ -0,0 +1,3 @@
+#!/bin/sh
+which rpcbind rpc.statd mount.nfs mount.nfs4 >/dev/null 2>&1 || exit 1
+exit 0
\ No newline at end of file