Implement msg_callback for SSL 2.0.

Important SSL 2.0 bugfixes (bugs found while implementing msg_callback).
diff --git a/ssl/ssl2.h b/ssl/ssl2.h
index a979c35..99a52ea 100644
--- a/ssl/ssl2.h
+++ b/ssl/ssl2.h
@@ -208,11 +208,11 @@
 		unsigned int conn_id_length;
 		unsigned int cert_type;	
 		unsigned int cert_length;
-		int csl; 
-		int clear;
+		unsigned int csl; 
+		unsigned int clear;
 		unsigned int enc; 
 		unsigned char ccl[SSL2_MAX_CERT_CHALLENGE_LENGTH];
-		int cipher_spec_length;
+		unsigned int cipher_spec_length;
 		unsigned int session_id_length;
 		unsigned int clen;
 		unsigned int rlen;