Add missing error path.

Error paths must always have OPENSSL_PUT_ERROR.

Change-Id: I0ed8c8288484a4ea69ec58317064ad3cd90ddd64
Reviewed-on: https://boringssl-review.googlesource.com/23104
Reviewed-by: Steven Valdez <svaldez@chromium.org>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

ssl/t1_lib.cc

diff --git a/ssl/t1_lib.cc b/ssl/t1_lib.cc
index a7bfec4..8d03623 100644
--- a/ssl/t1_lib.cc
+++ b/ssl/t1_lib.cc
@@ -2147,6 +2147,7 @@
   if (!CBS_get_u16(contents, &group_id) ||
       !CBS_get_u16_length_prefixed(contents, &peer_key) ||
       CBS_len(contents) != 0) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     *out_alert = SSL_AD_DECODE_ERROR;
     return false;
   }