Currently, WITHOUT_PORTSNAP forces WITHOUT_FREEBSD_UPDATE because the latter relies on phttpget, which lives inside the portsnap build bits.

Remove the dependency between these two options by moving phttpget out into ^/libexec and building/installing it if either WITH_PORTSNAP or WITH_FREEBSD_UPDATE. This isn't required at build-time, so it really should be as trivial as moving out.

Future work could remove the conditional if it's decided that users will use it independently of either the current in-base consumers.