meson: fix android vulkan build

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 448eb19158f483d807ef).

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

Fixes: 448eb19158f483d807ef ("vulkan: automatically compile the `display` platform when available")
Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Acked-by: Nataraj Deshpande <nataraj.deshpande@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5860>