Fix [-Wtype-limits] warning in LDAP by removing unnecessary condition

As context is a pointer to a berval struct and bv_len is of type
ber_len_t [1] which it self is defined as an unsigned integer [2]
this condition is always true.

[1] https://www.openldap.org/devel/gitweb.cgi?p=openldap.git;a=blob;f=include/lber.h#l212
[2] https://www.openldap.org/software//man.cgi?query=ber_free&sektion=3&apropos=0&manpath=OpenLDAP+2.4-Release

Author: Girgias

ext/ldap/ldap.c

@@ -257,7 +257,7 @@ static void _php_ldap_control_to_array(LDAP *ld, LDAPControl* ctrl, zval* array,
 			add_assoc_long(&value, "target", target);
 			add_assoc_long(&value, "count", count);
 			add_assoc_long(&value, "errcode", errcode);
-			if ( context && (context->bv_len >= 0) ) {
+			if (context) {
 				add_assoc_stringl(&value, "context", context->bv_val, context->bv_len);
 			}
 			add_assoc_zval(array, "value", &value);