Fix macOS guix build

[Sjors]

Looks like I broke something:

$ HOSTS="x86_64-apple-darwin arm64-apple-darwin" contrib/guix/guix-build
Found macOS SDK at '/home/guix/SDKs/Xcode-15.0-15A240d-extracted-SDK-with-libcxx-headers', using...
Checking that we can connect to the guix-daemon...

Hint: If this hangs, you may want to try turning your guix-daemon off and on
      again.

make: Entering directory '/home/guix/sv2-tp/depends'
make: Leaving directory '/home/guix/sv2-tp/depends'
make: Entering directory '/home/guix/sv2-tp/depends'
make: Leaving directory '/home/guix/sv2-tp/depends'
INFO: Building 1.0 for platform triple x86_64-apple-darwin:
      ...using reference timestamp: 1756292926
      ...running at most 32 jobs
      ...from worktree directory: '/home/guix/sv2-tp'
          ...bind-mounted in container to: '/bitcoin'
      ...in build directory: '/home/guix/sv2-tp/guix-build-1.0/distsrc-1.0-x86_64-apple-darwin'
          ...bind-mounted in container to: '/distsrc-base/distsrc-1.0-x86_64-apple-darwin'
      ...outputting in: '/home/guix/sv2-tp/guix-build-1.0/output/x86_64-apple-darwin'
          ...bind-mounted in container to: '/outdir-base/x86_64-apple-darwin'
      ADDITIONAL FLAGS (if set)
          ADDITIONAL_GUIX_COMMON_FLAGS: 
          ADDITIONAL_GUIX_ENVIRONMENT_FLAGS: 
          ADDITIONAL_GUIX_TIMEMACHINE_FLAGS: 
Required environment variables as seen inside the container:
    DIST_ARCHIVE_BASE: /outdir-base/dist-archive
    DISTNAME: sv2-tp-1.0
    HOST: x86_64-apple-darwin
    SOURCE_DATE_EPOCH: 1756292926
    JOBS: 32
    DISTSRC: /distsrc-base/distsrc-1.0-x86_64-apple-darwin
    OUTDIR: /outdir-base/x86_64-apple-darwin

Exit code is 1