ndk/media_format: Implement Debug in terms of Display (#450)

Currently `Debug` only prints a raw pointer which is rather useless to
look at.  In addition to the pointer, also print the `Display`
representation of `MediaFormat` which uses Android's `toString()`
function to create a human-readable string of the various fields set
inside of it.

On a side-note it is "great" to see that `toString()` is not currently
available as a user function via a lifetimed `CStr` as it is invalidated
in a nontrivial way (e.g. when `toString()` is called again, and
possibly also when `set_()` functions are called which are not currently
borrowing it mutably).

ndk/src/media/media_format.rs

@@ -14,7 +14,6 @@ use crate::media_error::{MediaError, Result};
 /// A native [`AMediaFormat *`]
 ///
 /// [`AMediaFormat *`]: https://developer.android.com/ndk/reference/group/media#amediaformat
-#[derive(Debug)]
 #[doc(alias = "AMediaFormat")]
 pub struct MediaFormat {
     inner: NonNull<ffi::AMediaFormat>,
@@ -29,6 +28,13 @@ impl fmt::Display for MediaFormat {
     }
 }
 
+impl fmt::Debug for MediaFormat {
+    #[doc(alias = "AMediaFormat_toString")]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "MediaFormat({:?}: {})", self.inner, self)
+    }
+}
+
 impl Default for MediaFormat {
     #[doc(alias = "AMediaFormat_new")]
     fn default() -> Self {