Add a new print-output build variable for the doc project, 'RLE'.

If defined, EPS files are run length encoded before being integrated
into the PostScript output.

  "make book.ps" currently generates a 96 megabyte file.
  "make RLE=1 book.ps" generates a 16 megabyte file.

If we added a tool to use better (LZW) compression for the eps
screenshots and such, then we could reduce this number further.

share/mk/doc.docbook.mk

@@ -90,6 +90,9 @@
 #                       a book.  This option may be an order of magnitude more
 #                       CPU intensive than the default build.
 #
+#       RLE             Use Run-Length Encoding for EPS files, this will
+#                       result in signficiantly smaller PostScript files, 
+#                       but may take longer for a printer to process.
 
 #
 # Documents should use the += format to access these.
@@ -169,6 +172,9 @@ PRINTOPTS+=    -V minimal-section-labels
 .if defined(TRACE)
 TEXCMDS+=	\tracingstats=${TRACE}
 .endif
+.if defined(RLE)
+PNMTOPSFLAGS+=	-rle
+.endif
 
 PERL?=		/usr/bin/perl
 PKG_CREATE?=	/usr/sbin/pkg_create