audio/surge-synthesizer-lv2: fix build on aarch64
armv7 should work, but the compiler crashes.
Approved by: portmgr (build fix blanket)
MFH: 2025Q3
Event: EuroBSDcon Devsummit 2025
(cherry picked from commit 8921bf5b397e78af405e28160173a5fe86cadb81)