Simplify tls1_change_cipher_spec.

Rather than use those weird bitmasks, just pass an evp_aead_direction_t
and figure it out from there.

Change-Id: Ie52c6404bd0728d7d1ef964a3590d9ba0843c1d6
Reviewed-on: https://boringssl-review.googlesource.com/20666
Reviewed-by: Steven Valdez <svaldez@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/handshake_server.cc b/ssl/handshake_server.cc
index cd99ec9..a38e25f 100644
--- a/ssl/handshake_server.cc
+++ b/ssl/handshake_server.cc
@@ -1397,7 +1397,7 @@
 }
 
 static enum ssl_hs_wait_t do_process_change_cipher_spec(SSL_HANDSHAKE *hs) {
-  if (!tls1_change_cipher_state(hs, SSL3_CHANGE_CIPHER_SERVER_READ)) {
+  if (!tls1_change_cipher_state(hs, evp_aead_open)) {
     return ssl_hs_error;
   }
 
@@ -1525,7 +1525,7 @@
   }
 
   if (!ssl->method->add_change_cipher_spec(ssl) ||
-      !tls1_change_cipher_state(hs, SSL3_CHANGE_CIPHER_SERVER_WRITE) ||
+      !tls1_change_cipher_state(hs, evp_aead_seal) ||
       !ssl3_send_finished(hs)) {
     return ssl_hs_error;
   }