Add a return value to prf_plus_t.allocate_bytes()

src/libstrongswan/crypto/prf_plus.h

@@ -44,8 +44,10 @@ struct prf_plus_t {
 	 *
 	 * @param length	number of bytes to get
 	 * @param chunk		chunk which will hold generated bytes
+	 * @return			TRUE if bytes allocated successfully
 	 */
-	void (*allocate_bytes) (prf_plus_t *this, size_t length, chunk_t *chunk);
+	__attribute__((warn_unused_result))
+	bool (*allocate_bytes) (prf_plus_t *this, size_t length, chunk_t *chunk);
 
 	/**
 	 * Destroys a prf_plus_t object.