dnssec-conf: depends libxslt-native

Fixed:
xmlto: Can't continue, xsltproc tool not found or not executable.
Makefile:20: recipe for target 'dnssec-configure.8' failed
make: *** [dnssec-configure.8] Error 3

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>