Replace wget with ftp as default in fetch scripts

Replace wget with ftp as default in fetch scripts

This default is overriden by curl when it is available on the system.

This allows for the fetch script to work on MINIX systems without any
additions from PKGSRC, while requiring either a netbsd compatible ftp or
curl to be installed on other systems.

Change-Id: Id79f799e1ef0f5fde6bb1c0e570984b7579519fb