Android: Bump ndk/ndk-glue to 0.3 and use constants for event ident (#1847)

Following the changes in [1] this bumps ndk and ndk-glue to 0.3 and uses
the new constants. The minor version has been bumped to prevent
applications from running an older winit (without #1826) with a newer
ndk/ndk-glue that does not pass this `ident` through the `data` pointer
anymore.

[1]: https://github.com/rust-windowing/android-ndk-rs/pull/112

src/platform_impl/android/mod.rs

@@ -31,8 +31,8 @@ enum EventSource {
 fn poll(poll: Poll) -> Option<EventSource> {
     match poll {
         Poll::Event { ident, .. } => match ident {
-            0 => Some(EventSource::Callback),
-            1 => Some(EventSource::InputQueue),
+            ndk_glue::NDK_GLUE_LOOPER_EVENT_PIPE_IDENT => Some(EventSource::Callback),
+            ndk_glue::NDK_GLUE_LOOPER_INPUT_QUEUE_IDENT => Some(EventSource::InputQueue),
             _ => unreachable!(),
         },
         Poll::Timeout => None,