Add AesGcmStream destructor with wc_AesFree

Author: JeremiahM37

scripts/build_ffi.py

@@ -649,6 +649,7 @@ def build_ffi(local_wolfssl, features):
             word32 sz, const byte* authIn, word32 authInSz);
         int wc_AesGcmDecryptFinal(Aes* aes, const byte* authTag,
             word32 authTagSz);
+        void wc_AesFree(Aes* aes);
         """
 
     if features["AES"] and features["AES_SIV"]:

wolfcrypt/ciphers.py

@@ -415,6 +415,9 @@ def __init__(self, key, IV, tag_bytes=16):
             if ret < 0:
                 raise WolfCryptError("Init error (%d)" % ret)
 
+        def __del__(self):
+            _lib.wc_AesFree(self._native_object)
+
         def set_aad(self, data):
             """
             Set the additional authentication data for the stream