Build fixes for MacOS

dtls.c

@@ -28,6 +28,7 @@
 #include <unistd.h>
 #include <openssl/err.h>
 #include <fcntl.h>
+#include <string.h>
 
 #include "openconnect.h"
 
@@ -175,9 +176,11 @@ int connect_dtls_socket(struct openconnect_info *vpninfo)
 	dtls_bio = BIO_new_socket(dtls_fd, BIO_NOCLOSE);
 	SSL_set_bio(dtls_ssl, dtls_bio, dtls_bio);
 
+#ifndef __APPLE__
 	/* XXX Cargo cult programming. Other DTLS code does this, and it might
 	   avoid http://rt.openssl.org/Ticket/Display.html?id=1703 */
         BIO_ctrl(dtls_bio, BIO_CTRL_DGRAM_MTU_DISCOVER, 0, NULL);
+#endif
 
 #ifndef SSL_OP_CISCO_ANYCONNECT
 #define SSL_OP_CISCO_ANYCONNECT 0x8000