devel/pika: builds fine on arm64

While the port builds now, it is likely not functional, on account of
20% of the unit tests failing with segfaults.

See also: https://github.com/pika-org/pika/issues/331
MFH: 2026Q1
Approved by: portmgr (build fix blanket)

(cherry picked from commit 9b3dc3acc0b8c6e4f1ab4c9e2b75dd92365213b6)