Repeated calls to AM_INIT_AUTOMAKE made fatal in 1.16.5:
https://git.savannah.gnu.org/cgit/automake.git/commit/?id=f4a3a70f69e1dbccb6578f39ef47835098a04624.

https://bugs.gentoo.org/818094
https://bugs.gentoo.org/827973

--- a/bin/configure.ac
+++ b/bin/configure.ac
@@ -4,8 +4,6 @@ AM_INIT_AUTOMAKE([foreign])
 AM_MAINTAINER_MODE
 AC_CANONICAL_HOST
 
-AM_INIT_AUTOMAKE
-
 AC_EXEEXT
 AC_OBJEXT