libpam: Disable nullok_secure

This will let us ssh with empty password as root user.
Its less secure but good for development work.

Signed-off-by: Khem Raj <raj.khem@gmail.com>

recipes-tweaks/pam/libpam_1.1.6.bbappend

@@ -0,0 +1,4 @@
+#allow empty password
+do_install_append () {
+	sed -i -e 's:nullok_secure:nullok:g' ${D}${sysconfdir}/pam.d/common-auth
+}