Initialize nonce in PerAEADTest.ABI.

Flagged by valgrind.

Change-Id: Ib49297bd483650880207a1efe5e9dff666e458d5
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/46204
Reviewed-by: Adam Langley <agl@google.com>

crypto/cipher_extra/aead_test.cc

diff --git a/crypto/cipher_extra/aead_test.cc b/crypto/cipher_extra/aead_test.cc
index bf02e78..deab26a 100644
--- a/crypto/cipher_extra/aead_test.cc
+++ b/crypto/cipher_extra/aead_test.cc
@@ -808,6 +808,7 @@
                             : sizeof(ad_buf) - 1;
 
   uint8_t nonce[EVP_AEAD_MAX_NONCE_LENGTH];
+  OPENSSL_memset(nonce, 'N', sizeof(nonce));
   const size_t nonce_len = EVP_AEAD_nonce_length(aead());
   ASSERT_LE(nonce_len, sizeof(nonce));