Fix compilation with GCC

Author: Midar

src/SSLConnectionFailedException.h

@@ -53,10 +53,10 @@ OF_ASSUME_NONNULL_BEGIN
 		     verifyResult: (long)verifyResult;
 - initWithHost: (OFString *)host
 	  port: (uint16_t)port
-	socket: (SSLSocket *)socket OF_UNAVAILABLE;
+	socket: (id)socket OF_UNAVAILABLE;
 - initWithHost: (OFString *)host
 	  port: (uint16_t)port
-	socket: (SSLSocket *)socket
+	socket: (id)socket
 	 errNo: (int)errNo OF_UNAVAILABLE;
 - initWithHost: (OFString *)host
 	  port: (uint16_t)port

src/SSLSocket.h

@@ -33,6 +33,7 @@ OF_ASSUME_NONNULL_BEGIN
 @interface SSLSocket: OFTCPSocket <OFTLSSocket>
 {
 	SSL *_SSL;
+	id <OFTLSSocketDelegate> _delegate;
 	OFString *_certificateFile, *_privateKeyFile;
 	const char *_privateKeyPassphrase;
 	bool _certificateVerificationEnabled;

src/SSLSocket.m

@@ -97,7 +97,7 @@ - (void)SSL_super_close;
 @implementation SSLSocket
 @synthesize delegate = _delegate, certificateFile = _certificateFile;
 @synthesize privateKeyFile = _privateKeyFile;
-@synthesize privateKeyPassphrase = privateKeyPassphrase;
+@synthesize privateKeyPassphrase = _privateKeyPassphrase;
 @synthesize certificateVerificationEnabled = _certificateVerificationEnabled;
 @synthesize requestClientCertificatesEnabled =
     _requestClientCertificatesEnabled;