Update Android port

* doc/emacs/input.texi (On-Screen Keyboards): Revise
documentation to reflect changes.

* src/keyboard.c (lispy_function_keys) <KEYCODE_DPAD_CENTER>:
Define select key absent out of negligence.

* src/xterm.c (syms_of_xterm) <x-quit-keysym>: Default to nil.
(bug#66040)

doc/emacs/input.texi

@@ -145,9 +145,10 @@ of a hardware button that is always present on the device results in
 Emacs quitting.  @xref{Quitting}.
 
 @vindex x-quit-keysym
-  Which button is used to do this depends on the window system in use:
-on X, it is defined in the variable @code{x-quit-keysym}, and on
-Android, it is always the volume down button.
+  The button afforded such special treatment varies; under X, no such
+button exists by default, but one can be configured through the
+variable @code{x-quit-keysym}, whereas under Android it is always the
+volume down buttons.
 
 @cindex text conversion, keyboards
   Most input methods designed to work with on-screen keyboards perform

src/keyboard.c

@@ -4989,6 +4989,10 @@ static const char *const lispy_accent_keys[] =
 #ifdef HAVE_ANDROID
 #define FUNCTION_KEY_OFFSET 0
 
+/* Mind that Android designates 23 KEYCODE_DPAD_CENTER, but it is
+   merely abstruse terminology for the ``select'' key frequently
+   located in certain physical keyboards.  */
+
 const char *const lispy_function_keys[] =
   {
     /* All elements in this array default to 0, except for the few
@@ -5025,6 +5029,7 @@ const char *const lispy_function_keys[] =
     [218] = "kana",
     [21]  = "left",
     [22]  = "right",
+    [23]  = "select",
     [24]  = "volume-up",
     [259] = "help",
     [25]  = "volume-down",

src/xterm.c

@@ -32812,17 +32812,12 @@ frame placement via frame parameters, `set-frame-position', and
 
 This is used to support quitting on devices that do not have any kind
 of physical keyboard, or where the physical keyboard is incapable of
-entering `C-g'.  It defaults to `XF86XK_AudioLowerVolume' on XFree86
-and X.Org servers, and is unset.
+entering `C-g'.
 
 The value is an alist associating between strings, describing X server
 vendor names, and a single number describing the keysym to use.  The
 keysym to use for each display connection is determined upon
 connection setup, and does not reflect further changes to this
 variable.  */);
-  Vx_quit_keysym
-    = list2 (Fcons (build_string ("The X.Org Foundation"),
-		    make_int (269025041)),
-	     Fcons (build_string ("The XFree86 Project, Inc."),
-		    make_int (269025041)));
+  Vx_quit_keysym = Qnil;
 }