biology/ncbi-cxx-toolkit: only for aarch64, amd64

This port uses SIMD intrincis to compute CRC checksums.
It's probably easy to add a generic code path if desired.

Approved by: portmgr (build fix blanket)
MFH: 2026Q1
Sponsored by: Raptor Computing Systems, LLC

(cherry picked from commit 2ea396c568c8df2627010da3d0f55ba9a98e7a85)