Switch to the more common idiom for scripts in genrules.

Bug: http://b/198619163
Test: treehugger
Change-Id: I8a6e9e179aef45e1b0622a2e15f80f92041f9736
diff --git a/tools/Android.bp b/tools/Android.bp
index dcd2a7d..d3ca28a 100644
--- a/tools/Android.bp
+++ b/tools/Android.bp
@@ -15,7 +15,7 @@
 
 subdirs = ["*"]
 
-filegroup {
-    name: "bionic-generate-version-script",
+python_binary_host {
+    name: "generate-version-script",
     srcs: ["generate-version-script.py"],
 }