[libvirt] [PATCH] docs: prefer to use rst2html5 instead of rst2html

[Daniel P. Berrangé]

Our website is written assuming HTML5 standard & doctype:

  commit b1c81567c7172bc9dcd701cf46ea3f87725d62c7
  Author: Daniel P. Berrangé <berrange at redhat.com>
  Date:   Wed Jul 26 18:01:25 2017 +0100

    docs: switch to using HTML5 doctype declaration

so we want the RST conversion to also use HTML5. Ubuntu 16.04 still
only has the HTML4 generating tools though, so we have that as a
fallback.

Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
---
 m4/virt-external-programs.m4 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/m4/virt-external-programs.m4 b/m4/virt-external-programs.m4
index ed634a4c73..aad21c81bf 100644
--- a/m4/virt-external-programs.m4
+++ b/m4/virt-external-programs.m4
@@ -33,10 +33,13 @@ AC_DEFUN([LIBVIRT_CHECK_EXTERNAL_PROGRAMS], [
   then
     AC_MSG_ERROR("xsltproc is required to build libvirt")
   fi
-  AC_PATH_PROGS([RST2HTML], [rst2html rst2html.py rst2html-3], [])
+
+  dnl Drop the rst2html  (aka HTML4) variants once we
+  dnl stop supporting Ubuntu 16.04 (Xenial)
+  AC_PATH_PROGS([RST2HTML], [rst2html5 rst2html5.py rst2html5-3 rst2html rst2html.py rst2html-3], [])
   if test -z "$RST2HTML"
   then
-    AC_MSG_ERROR("rst2html is required to build libvirt")
+    AC_MSG_ERROR("rst2html5/rst2html is required to build libvirt")
   fi
   AC_PATH_PROG([AUGPARSE], [augparse], [/usr/bin/augparse])
   AC_PROG_MKDIR_P
-- 
2.23.0