Move/dedupe some host path functions in package_ctx.go.

These functions don't need a PackageContext object.

Test: m
Bug: 145934348
Change-Id: Ia1da2c76cbad292f9ca79617199b2b5b6b265568
diff --git a/java/hiddenapi_singleton.go b/java/hiddenapi_singleton.go
index c0ef444..ad84cde 100644
--- a/java/hiddenapi_singleton.go
+++ b/java/hiddenapi_singleton.go
@@ -190,7 +190,7 @@
 	rule.MissingDeps(missingDeps)
 
 	rule.Command().
-		Tool(pctx.HostBinToolPath(ctx, "hiddenapi")).
+		Tool(ctx.Config().HostToolPath(ctx, "hiddenapi")).
 		Text("list").
 		FlagForEachInput("--boot-dex=", bootDexJars).
 		FlagWithInputList("--public-stub-classpath=", publicStubPaths, ":").