Remove s->renegotiate check in SSL_clear.

This dates back to upstream's a2a0158959.
It seems to be a remnant of those SSL_clear calls in the handshake state
machine which... were also bizarre and since gone.

Since SSL_clear is to drop the current connection but retain the
configuration, it doesn't really make sense to forbid it while you're
mid-handshake.

This removes another consumer of s->renegotiate.

BUG=429450

Change-Id: Ifac6bf11644447fd5571262bed7421684739bc39
Reviewed-on: https://boringssl-review.googlesource.com/4823
Reviewed-by: Adam Langley <agl@google.com>

ssl/ssl_lib.c

@@ -181,11 +181,6 @@ int SSL_clear(SSL *ssl) {
   ssl->hit = 0;
   ssl->shutdown = 0;
 
-  if (ssl->renegotiate) {
-    OPENSSL_PUT_ERROR(SSL, SSL_clear, ERR_R_INTERNAL_ERROR);
-    return 0;
-  }
-
   /* SSL_clear may be called before or after the |ssl| is initialized in either
    * accept or connect state. In the latter case, SSL_clear should preserve the
    * half and reset |ssl->state| accordingly. */
@@ -199,7 +194,7 @@ int SSL_clear(SSL *ssl) {
     assert(ssl->state == 0);
   }
 
-  /* TODO(davidben): Some state on |s| is reset both in |SSL_new| and
+  /* TODO(davidben): Some state on |ssl| is reset both in |SSL_new| and
    * |SSL_clear| because it is per-connection state rather than configuration
    * state. Per-connection state should be on |ssl->s3| and |ssl->d1| so it is
    * naturally reset at the right points between |SSL_new|, |SSL_clear|, and