Bug 1481864 - disable the sandbox on aarch64 windows by default; r=gps

The Chromium sandbox doesn't have the necessary arch-specific support.

old-configure.in

@@ -3099,6 +3099,13 @@ if test -n "$MOZ_TSAN" -o -n "$MOZ_ASAN"; then
     esac
 fi
 
+case "$OS_TARGET:$CPU_ARCH" in
+WINNT:aarch64)
+    # No sandbox support on AArch64 Windows.
+    MOZ_SANDBOX=
+    ;;
+esac
+
 MOZ_ARG_DISABLE_BOOL(sandbox,
 [  --disable-sandbox        Disable sandboxing support],
     MOZ_SANDBOX=,