Move AES128 above AES256 by default.

This is in preparation for adding AES_256_GCM in Chromium below AES_128_GCM.
For now, AES_128_GCM is preferable over AES_256_GCM for performance reasons.

While I'm here, swap the order of 3DES and RC4. Chromium has already disabled
RC4, but the default order should probably reflect that until we can delete it
altogether.

BUG=591516

Change-Id: I1b4df0c0b7897930be726fb8321cee59b5d93a6d
Reviewed-on: https://boringssl-review.googlesource.com/7296
Reviewed-by: Adam Langley <agl@google.com>

ssl/ssl_cipher.c

diff --git a/ssl/ssl_cipher.c b/ssl/ssl_cipher.c
index 7aa4a6f..9c9a441 100644
--- a/ssl/ssl_cipher.c
+++ b/ssl/ssl_cipher.c
@@ -1417,10 +1417,10 @@
    * AES_GCM. Of the two CHACHA20 variants, the new one is preferred over the
    * old one. */
   if (EVP_has_aes_hardware()) {
-    ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES256GCM, ~0u, 0, CIPHER_ADD, -1, 0,
-                          &head, &tail);
     ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES128GCM, ~0u, 0, CIPHER_ADD, -1, 0,
                           &head, &tail);
+    ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES256GCM, ~0u, 0, CIPHER_ADD, -1, 0,
+                          &head, &tail);
     ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_CHACHA20POLY1305, ~0u, 0, CIPHER_ADD,
                           -1, 0, &head, &tail);
     ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_CHACHA20POLY1305_OLD, ~0u, 0,
@@ -1430,24 +1430,24 @@
                           -1, 0, &head, &tail);
     ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_CHACHA20POLY1305_OLD, ~0u, 0,
                           CIPHER_ADD, -1, 0, &head, &tail);
-    ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES256GCM, ~0u, 0, CIPHER_ADD, -1, 0,
-                          &head, &tail);
     ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES128GCM, ~0u, 0, CIPHER_ADD, -1, 0,
                           &head, &tail);
+    ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES256GCM, ~0u, 0, CIPHER_ADD, -1, 0,
+                          &head, &tail);
   }
 
-  /* Then the legacy non-AEAD ciphers: AES_256_CBC, AES-128_CBC, RC4_128_SHA,
-   * RC4_128_MD5, 3DES_EDE_CBC_SHA. */
-  ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES256, ~0u, 0, CIPHER_ADD, -1, 0,
-                        &head, &tail);
+  /* Then the legacy non-AEAD ciphers: AES_128_CBC, AES_256_CBC,
+   * 3DES_EDE_CBC_SHA, RC4_128_SHA, RC4_128_MD5. */
   ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES128, ~0u, 0, CIPHER_ADD, -1, 0,
                         &head, &tail);
+  ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_AES256, ~0u, 0, CIPHER_ADD, -1, 0,
+                        &head, &tail);
+  ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_3DES, ~0u, 0, CIPHER_ADD, -1, 0, &head,
+                        &tail);
   ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_RC4, ~SSL_MD5, 0, CIPHER_ADD, -1, 0,
                         &head, &tail);
   ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_RC4, SSL_MD5, 0, CIPHER_ADD, -1, 0,
                         &head, &tail);
-  ssl_cipher_apply_rule(0, ~0u, ~0u, SSL_3DES, ~0u, 0, CIPHER_ADD, -1, 0, &head,
-                        &tail);
 
   /* Temporarily enable everything else for sorting */
   ssl_cipher_apply_rule(0, ~0u, ~0u, ~0u, ~0u, 0, CIPHER_ADD, -1, 0, &head,