fix for issue 1118: check if iv is zero in gcm.
1) found by roberto in mbedtls forum
2) if iv_len is zero, return an error
3) add tests for invalid parameters
diff --git a/tests/suites/test_suite_gcm.aes256_en.data b/tests/suites/test_suite_gcm.aes256_en.data
index 23d1689..0ff716d 100644
--- a/tests/suites/test_suite_gcm.aes256_en.data
+++ b/tests/suites/test_suite_gcm.aes256_en.data
@@ -670,6 +670,10 @@
depends_on:MBEDTLS_AES_C
gcm_encrypt_and_tag:MBEDTLS_CIPHER_ID_AES:"1477e189fb3546efac5cc144f25e132ffd0081be76e912e25cbce7ad63f1c2c4":"7bd3ea956f4b938ebe83ef9a75ddbda16717e924dd4e45202560bf5f0cffbffcdd23be3ae08ff30503d698ed08568ff6b3f6b9fdc9ea79c8e53a838cc8566a8b52ce7c21b2b067e778925a066c970a6c37b8a6cfc53145f24bf698c352078a7f0409b53196e00c619237454c190b970842bb6629c0def7f166d19565127cbce0":"c109f35893aff139db8ed51c85fee237":"8f7f9f71a4b2bb0aaf55fced4eb43c57415526162070919b5f8c08904942181820d5847dfd54d9ba707c5e893a888d5a38d0130f7f52c1f638b0119cf7bc5f2b68f51ff5168802e561dff2cf9c5310011c809eba002b2fa348718e8a5cb732056273cc7d01cce5f5837ab0b09b6c4c5321a7f30a3a3cd21f29da79fce3f3728b":"7841e3d78746f07e5614233df7175931e3c257e09ebd7b78545fae484d835ffe3db3825d3aa1e5cc1541fe6cac90769dc5aaeded0c148b5b4f397990eb34b39ee7881804e5a66ccc8d4afe907948780c4e646cc26479e1da874394cb3537a8f303e0aa13bd3cc36f6cc40438bcd41ef8b6a1cdee425175dcd17ee62611d09b02":32:"cb13ce59":0
+AES-GCM Bad IV (AES-256,128,0,0,32) #0
+depends_on:MBEDTLS_AES_C
+gcm_bad_parameters:MBEDTLS_CIPHER_ID_AES:MBEDTLS_GCM_DECRYPT:"ca264e7caecad56ee31c8bf8dde9592f753a6299e76c60ac1e93cff3b3de8ce9":"":"":"":32:MBEDTLS_ERR_GCM_BAD_INPUT
+
AES-GCM Selftest
depends_on:MBEDTLS_AES_C
gcm_selftest: