Add missing initialiser in e_chil.c

RT#2616
Reviewed-by: NTim Hudson <tjh@openssl.org>

engines/e_chil.c

@@ -1262,7 +1262,7 @@ static int hwcrhk_insert_card(const char *prompt_info,
     ui = UI_new_method(ui_method);
 
     if (ui) {
-        char answer;
+        char answer = '\0';
         char buf[BUFSIZ];
         /*
          * Despite what the documentation says wrong_info can be an empty