scripts/rebuild.sh: Remove 32-bit Darwin binaries.

We no longer support 32-bit binaries on Darwin, so don't even
try to build them with this script.
diff --git a/scripts/rebuild.sh b/scripts/rebuild.sh
index 34b648d..f0c5020 100755
--- a/scripts/rebuild.sh
+++ b/scripts/rebuild.sh
@@ -760,7 +760,6 @@
         ;;
     darwin-*)
         build_qemu_android darwin-x86_64
-        build_qemu_android darwin-x86
         ;;
     *)
         panic "Your operating system is not supported!"