Cast DNS SOA serial maximum boundary to long

This will fix i386 builds where the SOA serial value written
in API.txt was already of a long type while on x86_64 it was still
of an int type.

ipalib/plugins/dns.py

@@ -1585,7 +1585,7 @@ class dnszone(LDAPObject):
             label=_('SOA serial'),
             doc=_('SOA record serial number'),
             minvalue=1,
-            maxvalue=4294967295,
+            maxvalue=4294967295L,
             default_from=_create_zone_serial,
             autofill=True,
         ),