Do not run arm/arm64 mksnapshot binaries

For arm and arm64 target_arches, Chromium builds mksnapshot as an x64 binary and
as part of that build mksnapshot is executed to produce snapshot_blob.bin.
Chromium does not build native arm and arm64 binaries of mksnapshot, but
Electron does, so this patch makes sure that the build doesn't try to run
the mksnapshot binary if it was built for arm or arm64.

Patch-Filename: do_not_run_arm_arm64_mksnapshot_binaries.patch

BUILD.gn

@@ -1242,9 +1242,19 @@ if (v8_use_snapshot && v8_use_external_startup_data) {
     ]
     public_deps = [
       ":natives_blob",
-      ":run_mksnapshot_default",
     ]
 
+    if (v8_snapshot_toolchain == "//build/toolchain/linux:clang_arm" ||
+        v8_snapshot_toolchain == "//build/toolchain/linux:clang_arm64") {
+      public_deps += [
+        ":mksnapshot($v8_snapshot_toolchain)",
+      ]
+    } else {
+      public_deps += [
+        ":run_mksnapshot_default",
+      ]
+    }
+
     if (v8_use_multi_snapshots) {
       public_deps += [ ":run_mksnapshot_trusted" ]
     }