Make bindata relative to workspace root

This makes bindata relative to the Bazel workspace root instead of the package. This
puts it in line with general Bazel expectations about how files are laid out.

Test Plan: Should be covered by existing tests

X-Origin-Diff: phab/D613
GitOrigin-RevId: ce338fd40d24d6dd222c4fc02f48ada87b562d06
diff --git a/build/bindata/bindata.bzl b/build/bindata/bindata.bzl
index 23293c1..9420329 100644
--- a/build/bindata/bindata.bzl
+++ b/build/bindata/bindata.bzl
@@ -34,7 +34,7 @@
         "-pkg",
         ctx.attr.package,
         "-prefix",
-        ctx.label.package,
+        ctx.label.workspace_root,
         "-o",
         out,
     ])