Fix builing nuspell[tools] on Mingw

[dimztimz]

Describe the pull request

• What does your PR fix?

  Fixes building port nuspell on mingw triplet.

• Which triplets are supported/not supported? Have you updated the CI baseline?

All, Yes

• Does your PR follow the maintainer guide?

Yes

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

Yes

[github-actions]

Use the version scheme "version" instead of "version-string" in port "getopt".

You have modified or added at least one vcpkg.json where you should check the license field.

If you feel able to do so, please consider adding a "license" field to the following files:

• ports/getopt/vcpkg.json

Valid values for the license field can be found in the documentation

[JackBoosY]

Already tested feature tools on x86-windows.

[github-actions]

Use the version scheme "version" instead of "version-string" in port "getopt".

You have modified or added at least one vcpkg.json where you should check the license field.

If you feel able to do so, please consider adding a "license" field to the following files:

• ports/getopt/vcpkg.json

Valid values for the license field can be found in the documentation

[BillyONeal]

Thanks for the fix!