Set 2.4.50 release

CHANGES

 OpenLDAP 2.4 Change Log
 
-OpenLDAP 2.4.50 Engineering
+OpenLDAP 2.4.50 Release (2020/04/28)
 	Fixed client benign typos (ITS#8890)
 	Fixed libldap type cast (ITS#9175)
 	Fixed libldap retry loop in ldap_int_tls_connect (ITS#8650)

build/version.var

@@ -15,9 +15,9 @@
 ol_package=OpenLDAP
 ol_major=2
 ol_minor=4
-ol_patch=X
-ol_api_inc=20449
+ol_patch=50
+ol_api_inc=20450
 ol_api_current=12
-ol_api_revision=12
+ol_api_revision=13
 ol_api_age=10
-ol_release_date="2020/01/30"
+ol_release_date="2020/04/28"