GCC: do not populate AttestedCredentialData span parameters from initializer list.

A base::span parameter of AttestedCredentialData constructor was populated in
VirtualCtap2Device with an initializer list. But GCC cannot resolve that mapping.
So replace the initializer list by an explicit declaration of an array.

Bug: 819294
Change-Id: Id3f2d7978ab8adff3c5bf3fd8e25c1b16c872470
Reviewed-on: https://chromium-review.googlesource.com/1123823Reviewed-by: Jun Choi <hongjunchoi@chromium.org>
Commit-Queue: José Dapena Paz <jose.dapena@lge.com>
Cr-Commit-Position: refs/heads/master@{#572354}

device/fido/virtual_ctap2_device.cc

@@ -251,9 +251,10 @@ CtapDeviceResponseCode VirtualCtap2Device::OnMakeCredential(
   // Our key handles are simple hashes of the public key.
   auto hash = fido_parsing_utils::CreateSHA256Hash(public_key);
   std::vector<uint8_t> key_handle(hash.begin(), hash.end());
+  std::array<uint8_t, 2> sha256_length = {0, crypto::kSHA256Length};
 
   AttestedCredentialData attested_credential_data(
-      kDeviceAaguid, {{0, crypto::kSHA256Length}}, key_handle,
+      kDeviceAaguid, sha256_length, key_handle,
       ConstructECPublicKey(public_key));
 
   auto authenticator_data = ConstructAuthenticatorData(