[build] Fix multi-arch build for pointer-compression - part 2

Bug: v8:9899
Change-Id: Ia67d19e4b213db44a62c559a24a29ee6dd687810
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1876056Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64517}

BUILD.gn

@@ -225,9 +225,6 @@ if (v8_enable_pointer_compression == "") {
   # TODO(v8:v7703): temporarily enable pointer compression on arm64
   v8_enable_pointer_compression = v8_current_cpu == "arm64"
 }
-if (v8_enable_shared_ro_heap == "") {
-  v8_enable_shared_ro_heap = !v8_enable_pointer_compression
-}
 if (v8_enable_fast_torque == "") {
   v8_enable_fast_torque = v8_enable_fast_mksnapshot
 }
@@ -244,6 +241,9 @@ if (v8_multi_arch_build &&
     "clang_x64_pointer_compression") {
   v8_enable_pointer_compression = !v8_enable_pointer_compression
 }
+if (v8_enable_shared_ro_heap == "") {
+  v8_enable_shared_ro_heap = !v8_enable_pointer_compression
+}
 
 assert(!v8_disable_write_barriers || v8_enable_single_generation,
        "Disabling write barriers works only with single generation")