Allow BusyBox to be invoked as "<something>-busybox". This is
necessary when it's run from the Nix store as <hash>-busybox during
stdenv bootstrap.

--- busybox-1.24.2-orig/libbb/appletlib.c	2016-03-17 21:35:49.000000000 +0100
+++ busybox-1.24.2/libbb/appletlib.c	2016-09-25 08:48:18.293104041 +0200
@@ -779,7 +779,7 @@
 	int applet = find_applet_by_name(name);
 	if (applet >= 0)
 		run_applet_no_and_exit(applet, argv);
-	if (is_prefixed_with(name, "busybox"))
+	if (strstr(name, "busybox") != 0)
 		exit(busybox_main(argv));
 }