x11-fonts/fontsproto: missing dependency textproc/xmlto

[Yuri]

fontsproto uses xmlto utility if it is installed, and doesn't if it 
isn't installed.
But fontsproto has no dependency on xmlto, so it doesn't get rebuilt 
when fontsproto is rebuilt hierarchically. This is wrong.

x11-fonts/fontsproto/Makefile should have:
BUILD_DEPENDS = ${LOCALBASE}/bin/xmlto:${PORTSDIR}/textproc/xmlto
Or it could be made optional on a config option.

Yuri