Enable customization of the quit key on Android

* doc/emacs/android.texi (Android Windowing):

* doc/emacs/input.texi (On-Screen Keyboards): Document various
tidbits related to the quit key.

* java/org/gnu/emacs/EmacsNative.java (getQuitKeycode): New
function.

* java/org/gnu/emacs/EmacsWindow.java (EmacsWindow): Rename
`lastVolumeButtonRelease' to `lastQuitKeyRelease'.
(onKeyUp): Treat value returned by getQuitKeycode as the quit
key rather than mandate KEYCODE_VOLUME_DOWN.

* src/android.c (getQuitKeycode): Implement new function.

* src/androidterm.c (syms_of_androidterm)
<android_quit_keycode>: New variable.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/android.c b/src/android.c
index e44b58c5973..00a77fc398d 100644
--- a/src/android.c
+++ b/src/android.c
@@ -2645,6 +2645,13 @@ NATIVE_NAME (shouldForwardMultimediaButtons) (JNIEnv *env,
   return !android_pass_multimedia_buttons_to_system;
 }
 
+JNIEXPORT jint JNICALL
+NATIVE_NAME (getQuitKeycode) (JNIEnv *env, jobject object)
+{
+  /* Likewise.  */
+  return (jint) android_quit_keycode;
+}
+
 JNIEXPORT jboolean JNICALL
 NATIVE_NAME (shouldForwardCtrlSpace) (JNIEnv *env, jobject object)
 {