[sandbox] Use correct define when testing for Android

It should be V8_TARGET_OS_ANDROID instead of V8_OS_ANDROID.

Bug: chromium:1218005
Change-Id: I4b92977c5d8b70ca5023e30a966508965ea9f0fe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3706618Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81175}

include/v8-internal.h

@@ -188,7 +188,7 @@ using ExternalPointer_t = Address;
 #ifdef V8_ENABLE_SANDBOX
 
 // Size of the sandbox, excluding the guard regions surrounding it.
-#ifdef V8_OS_ANDROID
+#ifdef V8_TARGET_OS_ANDROID
 // On Android, most 64-bit devices seem to be configured with only 39 bits of
 // virtual address space for userspace. As such, limit the sandbox to 128GB (a
 // quarter of the total available address space).