Bug Description
-d directory contains magefiles directory does not work

What did you do?
$ mage -d DIR target

DIR contains magefiles directory.

What did you expect to happen?
Execute target in DIR/magefiles.

What actually happened?
mage stop with "No .go files marked with the mage build tag in this directory."

Environment

• Mage Version:
  Mage Build Tool v1.14.0
  Build Date: 2022-11-04T21:23:44+09:00
  Commit: 300bbc8
  built with: go1.19.2

• OS: windows msys2 / linux (WSL2)

Additional context
None