check_dns: add AAAA,MX,TXT,SRV,CNAME

[waja]

Just turning attached patch of github issue #894 into a push request.

"Added optional support for the major DNS record types (AAAA, MX, TXT, SRV, CNAME, A, ANY). Specifically, allow for a new optional --querytype parameter, and a new optional --accept-cname parameter. Help text has been updated to reflect the changes as well. Patch is against SVN trunk of check_dns.c from April 7,2009.

This change should be completely backwards compatible with existing check_dns usage and syntax. New features are off by default."

[pbiering]

take care when takeover, looks like the upstream version has a strange upcase issue:

/usr/lib64/nagios/plugins/check_dns -q SOA google.de
DNS OK: 0,023 seconds response time. GOOGle.de returns
ns2.google.com|time=0,022598s;;;0,000000

/usr/lib64/nagios/plugins/check_dns -q MX redhat.com
DNS OK: 0,043 seconds response time. REDHAt.com returns 10 mx2.REDHAt.com.,5 mx1.REDHAt.com.|time=0,042732s;;;0,000000

(amout of upcase chars vary....haven't digged through the code how this could happen...perhaps one can inform upstream)

/usr/lib64/nagios/plugins/check_dns -V
check_dns v2.0.1 (nagios-plugins 2.0.1)

[RincewindsHat]

As was discussed in #894 this should probably not implemented at all and check_dns should probably be deprecated for check_dig or something like that.