main/collectd: fix musl build

main/collectd/APKBUILD

@@ -24,6 +24,7 @@ source="http://collectd.org/files/collectd-$pkgver.tar.bz2
 _builddir="$srcdir"/$pkgname-$pkgver
 prepare() {
 	cd "$_builddir"
+	update_config_sub || return 1
 	for i in $source; do
 		case $i in
 		*.patch) msg $i; patch -p1 -i "$srcdir"/$i || return 1;;