meson: fix android vulkan build

Android doesn't have `pthread_cancel()` and is unlikely to ever
implement it [1], but `wsi_common_display.c` needs it (or an
alternative).

Let's just disable the platform on Android (as it used to be
before 448eb191).

[1] https://android-review.googlesource.com/c/platform/bionic/+/1215779/1/docs/status.md

Fixes: 448eb191 ("vulkan: automatically compile the `display` platform when available")
Signed-off-by: Eric Engestrom <eric@engestrom.ch>
1 job for fix-android in 17 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Success
passed #3566699
success

00:00:17