tools: require autoconf version 2.69 or higher

Signed-off-by: Rafaël Carré <funman@videolan.org>
(cherry picked from commit d2ff1914069d054c2a0a3c13825faccb81c64546)
Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>

extras/tools/bootstrap

@@ -70,7 +70,7 @@ else
 fi
 }
 
-check autoconf 2.67
+check autoconf 2.69
 check automake 1.11
 check m4 1.4.16
 check libtool 2.4