turnip: Don't expose VK_ANDROID_native_buffer on non-Android.

The code is only there when compiling that platform.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7014>
diff --git a/src/freedreno/vulkan/tu_extensions.py b/src/freedreno/vulkan/tu_extensions.py
index 3eeffad..d34cb59 100644
--- a/src/freedreno/vulkan/tu_extensions.py
+++ b/src/freedreno/vulkan/tu_extensions.py
@@ -74,7 +74,7 @@
     Extension('VK_EXT_sample_locations',                  1, 'device->gpu_id == 650'),
     Extension('VK_EXT_sampler_filter_minmax',             1, True),
     Extension('VK_EXT_transform_feedback',                1, True),
-    Extension('VK_ANDROID_native_buffer',                 1, True),
+    Extension('VK_ANDROID_native_buffer',                 1, 'ANDROID'),
     Extension('VK_KHR_external_fence',                    1, True),
     Extension('VK_KHR_external_fence_fd',                 1, True),
     Extension('VK_KHR_external_semaphore',                1, True),