add configure script

.gitignore

@@ -10,3 +10,4 @@
 /x86_64-cross/*.xz
 /x86_64-cross/binutils-*/
 /x86_64-cross/gcc-*/
+/build/

Rsconscript

@@ -0,0 +1,3 @@
+configure do
+  check_c_compiler "x86_64-elf-gcc", on_fail: "Install cross compiler from x86_64-cross directory"
+end

configure

@@ -0,0 +1,2 @@
+#!/bin/sh
+exec ./rscons configure "$@"