shortcuts: Reduce SHORTCUTS_PER_HANDLE to 4

The current value of 32 per handle seems excessive. Buflib overhead
per handle is only 20 bytes and a single shortcut is > 500 bytes.
Reducing SHORTCUTS_PER_HANDLE means that minimum memory usage can
be lower when there are a few shortcuts, at the cost of marginally
increased usage for large numbers of shortcuts. This is helpful to
keep memory usage under control for low-memory targets, where 16 KiB
is almost 1% of system RAM!

Change-Id: I47dbe0da874ae512cf50a0bd8350576ab2fabdf4

apps/shortcuts.c

@@ -80,7 +80,7 @@ struct shortcut {
         } timedata;
     } u;
 };
-#define SHORTCUTS_PER_HANDLE 32
+#define SHORTCUTS_PER_HANDLE 4
 struct shortcut_handle {
     struct shortcut shortcuts[SHORTCUTS_PER_HANDLE];
     int next_handle;