add numerical recipes library

lib/nr/ansi/examples/xscrsho.c

@@ -0,0 +1,18 @@
+
+/* Driver for routine scrsho */
+
+#include <stdio.h>
+#define NRANSI
+#include "nr.h"
+
+static float fx(float x)
+{
+	return bessj0(x);
+}
+
+int main(void)
+{
+	scrsho(fx);
+	return 0;
+}
+#undef NRANSI