Don't produce HTML files if utility programs are missing.

* Makefile.in (make_html, make_install_html): New variables.
(MDEFINES): Updated.

* aclocal.m4 (GROFF_HTML_PROGRAMS): New function to test for HTML
utility programs.
* configure.ac: Use it.
* configure: Regenerated.

* doc/Makefile.sub (PROCESSEDEXAMPLEFILES): Move webpage.html to...
(HTMLEXAMPLESFILES): This new variable.
(EXAMPLESIMAGEFILES): Renamed to...
(HTMLEXAMPLEIMAGEFILES): This.
(CLEANADD): Add HTMLEXAMPLEFILES.
(all): Use `make_html'.
(html): New target.
(install_data): Use `make_install_html'.
Move html stuff to...
(install_html): This new target.
(uninstall_sub): Updated.

1 files changed, 25 insertions, 0 deletions

diff --git a/aclocal.m4 b/aclocal.m4
index 4d41ba03..a2c497b0 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -58,6 +58,31 @@ AC_DEFUN(GROFF_PROG_YACC,
 [AC_CHECK_PROGS(YACC, byacc 'bison -y', yacc)])dnl
 dnl
 dnl
+dnl The following programs are needed for grohtml.
+dnl
+AC_DEFUN(GROFF_HTML_PROGRAMS,
+[make_html=html
+make_install_html=install_html
+AC_CHECK_PROG(pnmcut, pnmcut, found, missing)
+AC_CHECK_PROG(pnmcrop, pnmcrop, found, missing)
+AC_CHECK_PROG(pnmtopng, pnmtopng, found, missing)
+AC_CHECK_PROG(gs, gs gsos2, found, missing)
+AC_CHECK_PROG(psselect, psselect, found, missing)
+case "x$pnmcut$pnmcrop$pnmtopng$gs$psselect" in
+*missing*)
+	make_html=
+	make_install_html=
+	AC_MSG_WARN([
+
+  Since one or more of the above five programs can't be found in the path,
+  the HTML backend of groff (grohtml) won't work properly.  Consequently,
+  no documentation in HTML format is built and installed.
+]) ;;
+esac
+AC_SUBST(make_html)
+AC_SUBST(make_install_html)])dnl
+dnl
+dnl
 dnl GROFF_CSH_HACK(if hack present, if not present)
 dnl
 AC_DEFUN(GROFF_CSH_HACK,