midori: add librsvg-native to DEPENDS

configure found rsvg-convert on host:
...
Checking for program rsvg-convert           : /usr/bin/rsvg-convert
...

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
Acked-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>