Make WXK_LAUNCH_x constants consecutive

No real changes, but don't complicate the constants definitions
needlessly just to avoid changing the numeric value of WXK_LAUNCH_APP
constants as nobody should rely on them anyhow.

Not doing it simplifies things and allows to condense the mapping from
GDK keys to wx ones.

include/wx/defs.h

@@ -2433,8 +2433,9 @@ enum wxKeyCode
     WXK_MEDIA_STOP,
     WXK_MEDIA_PLAY_PAUSE,
     WXK_LAUNCH_MAIL,
-    WXK_LAUNCH_APP1,
-    WXK_LAUNCH_APP2,
+
+    // Events for these keys are currently only generated by wxGTK, with the
+    // exception of WXK_LAUNCH_{A,B}, see WXK_LAUNCH_APP{1,2} below.
     WXK_LAUNCH_0,
     WXK_LAUNCH_1,
     WXK_LAUNCH_2,
@@ -2445,14 +2446,17 @@ enum wxKeyCode
     WXK_LAUNCH_7,
     WXK_LAUNCH_8,
     WXK_LAUNCH_9,
-    /* Alias for backwards compatibility with old gtk bindings,
-     * then continue from LAUNCH_9 */
-    WXK_LAUNCH_A = WXK_LAUNCH_APP1,
-    WXK_LAUNCH_B = WXK_LAUNCH_APP2,
-    WXK_LAUNCH_C = WXK_LAUNCH_9 + 1,
+    WXK_LAUNCH_A,
+    WXK_LAUNCH_B,
+    WXK_LAUNCH_C,
     WXK_LAUNCH_D,
     WXK_LAUNCH_E,
-    WXK_LAUNCH_F
+    WXK_LAUNCH_F,
+
+    // These constants are the same as the corresponding GTK keys, so give them
+    // the same value, but they are also generated by wxMSW.
+    WXK_LAUNCH_APP1 = WXK_LAUNCH_A,
+    WXK_LAUNCH_APP2 = WXK_LAUNCH_B
 };
 
 /* This enum contains bit mask constants used in wxKeyEvent */