Verify the formatting of every .v file in the V repository.

Usage:
  v test-fmt [compiler flags...]

The command runs `v fmt` over all .v files found in the checkout,
excluding a small list of known exceptions, and reports every file,
that is not correctly formatted.

Use `v fmt -w <file>` to format just your own files; this command is
mostly used to verify a whole checkout, before submitting PRs.
