Results 4 issues of Bryan FRIMIN

This extension seems to have been used before to extend the OpenAPI v2 format, but it is not used anymore as OpenAPI v3 offers a mechanism for polymorphic objects.

This was introduced in [2019](https://github.com/freebsd/poudriere/commit/5c0ca1b2960bc565176b9462a5f643664f10d1ad) when pkg open `/dev/null` after doing the chroot. In the [next release](https://github.com/freebsd/pkg/commit/5a0cc7f37e783a636e11f5499f5f8449ed318e0e) of pkg, this should not be required anymore as pkg will open `/dev/null`...

Allows the use of the script on FreeBSD and other systems that do not install perl in the `/usr/bin` folder.