Add command variables for PS2EPS, PIC2PS, and groff so that we can use

PIC diagrams in the doc tree.

share/mk/doc.docbook.mk

@@ -180,6 +180,7 @@ XARGS?=		/usr/bin/xargs
 TEX?=		${PREFIX}/bin/tex
 LATEX?=		${PREFIX}/bin/latex
 PDFTEX?=	${PREFIX}/bin/pdftex
+GROFF?=		groff
 TIDY?=		${PREFIX}/bin/tidy
 TIDYOPTS?=	-i -m -raw -preserve -f /dev/null ${TIDYFLAGS}
 HTML2TXT?=	${PREFIX}/bin/links

share/mk/doc.images.mk

@@ -105,6 +105,8 @@ PNMTOPS?=	${PREFIX}/bin/pnmtops
 PNMTOPSOPTS?=	-noturn ${PNMTOPSFLAGS}
 EPSTOPDF?=	${PREFIX}/bin/epstopdf
 EPSTOPDFOPTS?=	${EPSTOPDFFLAGS}
+PS2EPS?=	${PREFIX}/bin/ps2epsi
+PIC2PS?=	${GROFF} -p -S -Wall -mtty-char -man 
 
 # Use suffix rules to convert .scr files to .png files
 .SUFFIXES:	.scr .png .eps