Remove SSL_OP_TLS_D5_BUG.

This dates to SSLeay 0.9.0. The Internet seems to have completely
forgotten what "D5" is. (I can't find reference to it beyond
documentation of this quirk.) The use counter we added sees virtually no
hits.

Change-Id: I9781d401acb98ce3790b1b165fc257a6f5e9b155
Reviewed-on: https://boringssl-review.googlesource.com/6557
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/key_agreement.go b/ssl/test/runner/key_agreement.go
index 4a07ed7..f65ff6e 100644
--- a/ssl/test/runner/key_agreement.go
+++ b/ssl/test/runner/key_agreement.go
@@ -156,7 +156,7 @@
 		return nil, nil, err
 	}
 	ckx := new(clientKeyExchangeMsg)
-	if clientHello.vers != VersionSSL30 && !config.Bugs.SSL3RSAKeyExchange {
+	if clientHello.vers != VersionSSL30 {
 		ckx.ciphertext = make([]byte, len(encrypted)+2)
 		ckx.ciphertext[0] = byte(len(encrypted) >> 8)
 		ckx.ciphertext[1] = byte(len(encrypted))