Architecture-specific options are evaluated for host arch, not jail arch

[clausecker]

When interactively configuring a port with poudriere testport -c, the options seem to be configured for the architecture of the host, not of the jail. So e.g. when building on an amd64 host with an i386 jail and the port has

OPTIONS_DEFINE_i386= FOO

then Poudriere does not show the option FOO as available.