dev-rust/dbus-codegen: Set slot to 0/${PVR}

This installs a binary to /usr/bin which makes it conflict with other
versions of the same package.

BUG=chromium:1129542
TEST=emerge-${BOARD} dev-rust/dbus-codegen

Change-Id: Ie9f9cb8ed0cb84e343ead876d455e317f06e6f2c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/2416972
Tested-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Benjamin Gordon <bmgordon@chromium.org>
Commit-Queue: Allen Webb <allenwebb@google.com>
2 files changed