Cleanup comment that should've been removed

The previous change, I237f5663b0f8b060f6df130de04e17e2b1695f8a, removed
a SETUPTOOLS flag, but not the comment explaining why that flag was
previously set. Clean up that comment.

Change-Id: I32b0240fd56310d7f10596aaa8ef432679bfd66a
1 file changed