ck_ht: Set artificial key length limit if pointer packing is disabled.

include/ck_ht.h

@@ -53,6 +53,8 @@ enum ck_ht_mode {
 #define CK_HT_PP
 #define CK_HT_KEY_LENGTH ((sizeof(void *) * 8) - CK_MD_VMA_BITS)
 #define CK_HT_KEY_MASK   ((1U << CK_HT_KEY_LENGTH) - 1)
+#else
+#define CK_HT_KEY_LENGTH 65535
 #endif
 
 struct ck_ht_entry {