main/varnish: update config.sub

configure: error: /bin/sh build-aux/config.sub riscv64-alpine-linux-musl failed

main/varnish/APKBUILD

@@ -45,6 +45,10 @@ esac
 
 prepare() {
 	default_prepare
+
+	# Fix build with riscv64
+	update_config_sub
+
 	# vnum_c_test is broken in 7.0.0 (but will be fixed for 7.1)
 
 	if [ "$CARCH" = x86 ]; then