configure.ac: complain when xmlto cannot be found

related to #338

diff --git a/configure.ac b/configure.ac
index 932236671da56db36d137d35b7390e14af0b7589..9657e3f9e3a2ede6e40dd0b3ee44615b755f3806 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -102,7 +102,9 @@ AC_PROG_RANLIB
 AC_PROG_LN_S
 
 AC_PATH_PROG([PATH_ASCIIDOC], [asciidoc])
-AC_PATH_PROG([PATH_XMLTO], [xmlto])
+AC_PATH_PROG([PATH_XMLTO], [xmlto], [no])
+AS_IF([test x"$PATH_XMLTO" = x"no"],
+      [AC_MSG_ERROR([xmlto is required for generating man pages])])
 
 AM_PROG_AR