audio/mumble: Fix build with OpenSSL 3 and later

Approved by:	portmgr (blanket)

audio/mumble/files/patch-src_SelfSignedCertificate.cpp

+--- src/SelfSignedCertificate.cpp.orig	2023-06-10 11:50:34 UTC
++++ src/SelfSignedCertificate.cpp
+@@ -45,10 +45,12 @@ bool SelfSignedCertificate::generate(CertificateType c
+ 	QString commonName;
+ 	bool isServerCert = certificateType == CertificateTypeServerCertificate;
+ 
++#ifdef CRYPTO_MEM_CHECK_ON
+ 	if (CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ON) == -1) {
+ 		ok = false;
+ 		goto out;
+ 	}
++#endif
+ 
+ 	x509 = X509_new();
+ 	if (x509 == NULL) {