Replace hashtable key if a put operation replaces value

Fixes a crash if lifetime of key is bound to value (i.e. key == value)

src/libstrongswan/utils/hashtable.c

@@ -249,6 +249,7 @@ METHOD(hashtable_t, put, void*,
 			{
 				old_value = pair->value;
 				pair->value = value;
+				pair->key = key;
 				break;
 			}
 		}