net-snmp: fix for Security Advisory - CVE-2014-3565

snmplib/mib.c in net-snmp 5.7.0 and earlier, when the -OQ option is used,
allows remote attackers to cause a denial of service (snmptrapd crash) via
a crafted SNMP trap message, which triggers a conversion to the variable
type designated in the MIB file, as demonstrated by a NULL type in an ifMtu
trap message.

http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-3565



Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>