Bug fix for X.509 two-digit year.

Pointed out by Alexander Tyshlek <tyshlek@fuib.com> and Peter Gutmann
<pgut001@cs.auckland.ac.nz>

crypto/x509/x509_vfy.c

@@ -449,9 +449,9 @@ ASN1_UTCTIME *ctm;
 	X509_gmtime_adj(&atm,-offset);
 
 	i=(buff1[0]-'0')*10+(buff1[1]-'0');
-	if (i < 70) i+=100;
+	if (i < 50) i+=100;
 	j=(buff2[0]-'0')*10+(buff2[1]-'0');
-	if (j < 70) j+=100;
+	if (j < 50) j+=100;
 
 	if (i < j) return (-1);
 	if (i > j) return (1);