Fix warnings: message.c: copy_hotkeys_and_msg: Garbage value: FP. #2062

Problem    : Branch condition evaluates to a garbage value @ 2868.
Diagnostic : False positive.
Rationale  : Array has_hotkey, declared at 2812, is initialized by
             console_dialog_alloc (only the needed number of elements).
             That same number of elements is used by
             copy_hotkeys_and_msg.
             Suggested path error is impossible, because it involves a
             different number of elements in those functions.
Resolution : Above condition is cumbersome to prove through assertions.
             Thus, we prefer to just initialize the array to all-false
             at declaration point before calling console_dialog_alloc.

src/nvim/message.c

@@ -2809,7 +2809,7 @@ static char_u * console_dialog_alloc(const char_u *message,
 static char_u *msg_show_console_dialog(char_u *message, char_u *buttons, int dfltbutton)
   FUNC_ATTR_NONNULL_RET
 {
-  bool has_hotkey[HAS_HOTKEY_LEN];
+  bool has_hotkey[HAS_HOTKEY_LEN] = {false};
   char_u *hotk = console_dialog_alloc(message, buttons, has_hotkey);
 
   copy_hotkeys_and_msg(message, buttons, dfltbutton, has_hotkey, hotk);