btrfs-progs: configure: check if xmlto exists at configure time

AC_PATH_PROG won't fail even if it fails to find command path.
xmlto is required for document build and we should report error
if it doesn't exist at configure time.

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/configure.ac b/configure.ac
index af13a95..a4c98b3 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -93,7 +93,11 @@ AC_SUBST([DISABLE_DOCUMENTATION])
 dnl detect tools to build documentation
 ASCIIDOC_TOOL="none"
 if test "x$enable_documentation" = xyes; then
-       AC_PATH_PROG([XMLTO], [xmlto], [xmlto])
+       AC_PATH_PROG([XMLTO], [xmlto])
+       if test -z "$XMLTO"; then
+               AC_MSG_ERROR([cannot find xmlto, cannot build documentation])
+       fi
+
        AC_PATH_PROG([GZIP], [gzip], [gzip])
        AC_PATH_PROG([MV], [mv], [mv])
        AC_PROG_SED