Fix gcc compilation error.

QUICHE fails to compile with gcc with the following error message:

quic/core/quic_crypto_stream.cc: In constructor 'QuicCryptoStream::QuicCryptoStream(QuicSession*)':
quic/core/quic_crypto_stream.cc:39:52: error: use of deleted function 'QuicCryptoStream::CryptoSubstream::CryptoSubstream(QuicCryptoStream::CryptoSubstream&&)'
                   {this, ENCRYPTION_FORWARD_SECURE}} {
                                                    ^
In file included from quic/core/quic_crypto_stream.cc:5:
quic/core/quic_crypto_stream.h:158:30: note: 'QuicCryptoStream::CryptoSubstream::CryptoSubstream(QuicCryptoStream::CryptoSubstream&&)' is implicitly deleted because the default definition would be ill-formed:
   struct QUIC_EXPORT_PRIVATE CryptoSubstream {
                              ^~~~~~~~~~~~~~~
quic/core/quic_crypto_stream.h:158:30: error: use of deleted function 'QuicStreamSendBuffer::QuicStreamSendBuffer(QuicStreamSendBuffer&&)'
In file included from quic/core/quic_stream.h:27,
                 from quic/core/quic_crypto_stream.h:15,
                 from quic/core/quic_crypto_stream.cc:5:
quic/core/quic_stream_send_buffer.h:65:3: note: declared here
   QuicStreamSendBuffer(QuicStreamSendBuffer&& other) = delete;
   ^~~~~~~~~~~~~~~~~~~~

This CL changes QuicCryptoStrem::substreams_ type from array to std::array, and
uses aggregate initialization instead of initializer list as required for
std::array.  See also
https://stackoverflow.com/questions/8192185/using-stdarray-with-initialization-lists

I manually confirmed that this compiles in Chromium using clang, and compiles in
Envoy using either gcc or clang.  I have no idea why.

gfe-relnote: n/a, no functional change.
PiperOrigin-RevId: 284051434
Change-Id: I936020d8847e8109e73b9ffe1493ca1b74e159dc
diff --git a/quic/core/quic_crypto_stream.cc b/quic/core/quic_crypto_stream.cc
index e22e830..3bc94e8 100644
--- a/quic/core/quic_crypto_stream.cc
+++ b/quic/core/quic_crypto_stream.cc
@@ -33,10 +33,10 @@
           QuicVersionUsesCryptoFrames(session->transport_version())
               ? CRYPTO
               : BIDIRECTIONAL),
-      substreams_{{this, ENCRYPTION_INITIAL},
-                  {this, ENCRYPTION_HANDSHAKE},
-                  {this, ENCRYPTION_ZERO_RTT},
-                  {this, ENCRYPTION_FORWARD_SECURE}} {
+      substreams_{{{this, ENCRYPTION_INITIAL},
+                   {this, ENCRYPTION_HANDSHAKE},
+                   {this, ENCRYPTION_ZERO_RTT},
+                   {this, ENCRYPTION_FORWARD_SECURE}}} {
   // The crypto stream is exempt from connection level flow control.
   DisableConnectionFlowControlForThisStream();
 }