scudo: Fix compilation for non-Linux aarch64

Linux-specific aarch64 code was deconditionalized in commit
dfa40840e0e2fa094c5d3f441affe0785cdc8d09.  This broke builds for
non-Linux aarch64 platforms.

Reviewed By: cryptoad

Differential Revision: https://reviews.llvm.org/D94108

GitOrigin-RevId: 90b8fd6136078127f5b792ec64745e5ae54a12a4
1 file changed