fix(nix): keep Intel Darwin info tables with their entry code

Mark x86 Mach-O info entries as alternate entries in both GHC stages, so LLD preserves tables-next-to-code. Add a production compiler object/link regression to the existing Intel CI job.

.github/workflows/nix.yml

@@ -110,6 +110,11 @@ jobs:
         shell: bash
         run: make nix-build 2>&1 | tee nix-build.log
 
+      - name: Check native Intel Darwin GHC info-table placement
+        if: ${{ matrix.system == 'x86_64-darwin' && matrix.target == 'all' }}
+        timeout-minutes: 10
+        run: nix build .#checks.x86_64-darwin.ghc-macho-info-tables --no-link -L --max-jobs 1 --timeout 300
+
       # Diagnose the same native library after failure. Keep the canonical
       # failure and its flags intact; this is a separate diagnostic derivation.
       - name: Trace native Linux GHC and capture faults after failure