Patch to make it build with clang.

print/htmldoc/Makefile

@@ -1,10 +1,11 @@
-# $OpenBSD: Makefile,v 1.38 2017/04/10 11:46:33 sthen Exp $
+# $OpenBSD: Makefile,v 1.39 2017/04/18 20:16:33 benoit Exp $
 
 COMMENT =		convert HTML pages to PDF/PS format
 
 V =			1.8.29
 DISTNAME =		htmldoc-${V}
 CATEGORIES =		print www
+REVISION =		0
 
 HOMEPAGE =		http://www.msweet.org/projects.php?Z1
 

print/htmldoc/patches/patch-htmldoc_htmlsep_cxx

@@ -0,0 +1,12 @@
+$OpenBSD: patch-htmldoc_htmlsep_cxx,v 1.1 2017/04/18 20:16:33 benoit Exp $
+--- htmldoc/htmlsep.cxx.orig	Tue Apr 18 21:47:10 2017
++++ htmldoc/htmlsep.cxx	Tue Apr 18 21:49:15 2017
+@@ -524,7 +524,7 @@
+     if (t->markup >= MARKUP_H1 && t->markup < (MARKUP_H1 + TocLevels) &&
+         htmlGetVariable(t, (uchar *)"_HD_OMIT_TOC") == NULL)
+     {
+-      if (heading >= 0)
++      if (*heading >= 0)
+         write_footer(out, *heading);
+ 
+       (*heading) ++;