variant: check for gen_config on the PATH before running

This ensures that gen_config is available before the script runs, and
fails with instructions for adding it if it is not available.

TEST=remove gen_config from path and run directly,
  then again after adding to path with the instructions from the script.

Change-Id: I39f684d24ffdd0205652f7c3d900621f88f28bb3
Reviewed-by: Paul Fagerburg <>
Commit-Queue: Matthew Ziegelbaum <>
Tested-by: Matthew Ziegelbaum <>
1 file changed