am-utils-6.2 - dont prevent autoconf 2.7 build

From: Ian Kent <raven@themaw.net>

Fedora is updating to autoconf 2.71, stop bootstrap from preventing
the build.

Signed-off-by: Ian Kent <raven@themaw.net>
---
 bootstrap |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/bootstrap b/bootstrap
index 000b0167..d454c631 100755
--- a/bootstrap
+++ b/bootstrap
@@ -9,7 +9,8 @@ validateversion() {
     local v="$(autoreconf --version 2>&1 | head -1)"
     case "$v" in
     *2.69)	;;
-    *)		echo "am-utils requires autoconf 2.69, you have:"
+    *2.71)	;;
+    *)		echo "am-utils requires autoconf 2.69 or 2.71, you have:"
 		echo "	$v"
 		exit 1;;
     esac