add build test for check_cfg - close #59

build_tests/configure/check_cfg.rb

@@ -0,0 +1,7 @@
+configure do
+  check_cfg program: "my-config"
+end
+
+Rscons::Environment.new(echo: :command) do |env|
+  env.Program("myconfigtest", "simple.c")
+end

build_tests/configure/simple.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main(int argc, char *argv[])
+{
+    printf("This is a simple C program\n");
+}