Remove hard coded genie binary to enable depending on devel/genie.

--- 3rdparty/bx/makefile.orig	2023-10-23 15:53:41 UTC
+++ 3rdparty/bx/makefile
@@ -3,7 +3,7 @@
 # License: https://github.com/bkaradzic/bx/blob/master/LICENSE
 #
 
-GENIE=../bx/tools/bin/$(OS)/genie
+GENIE=%%GENIE_PREFIX%%genie
 
 all:
 	$(GENIE)                       vs2017