Log Message:
emulators/compat80: Fold MESSAGE into DESCR

It was just warning that the package, documented to contain shared
libraries, needs a kernel with COMPAT_80 to be useful.  Add that as a
parenthetical remark in DESCR while explaining what the package
contains, making it clear that it doesn't also include NetBSD kernels.

Drop comment about NetBSD 9 still being in beta.