autogen.sh: Switch from bash to sh and make it POSIX
diff --git a/autogen.sh b/autogen.sh
index 02ca644..a47d80e 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -1,11 +1,11 @@
-#!/bin/bash
+#!/bin/sh
# Run this to set up the build system: configure, makefiles, etc.
# We trust that the user has a recent enough autoconf & automake setup
# (not older than a few years...)
test_program_errors=0
-function test_program {
+test_program () {
if ! command -v $1 >/dev/null 2>&1 ; then
echo "Missing program '$1'."
test_program_errors=1