net-mgmt/chillispot: Omit special GCC 4.2 handling

Remove code catering to GCC 4.2 (as system compiler) which is not
necessary any longer: USES=compiler never pulls that in anymore.

This reverts commit 92e22122e819280ea0c18de3ddd7a8b8a25a3ead (and
part of 24b49f43d56fb1138da51ee1bcd08a7f6278b61f) from 3+ years ago.

Approved by: maintainer (Sevan Janiyan <venture37@geeklan.co.uk>)