fixes PowerDNS/pdns/#661

I was doing some performance testing on our 32-way servers and discovered that in the simple case where the test program returns the data straight away, about 80% of the time was being spent in the kernel in a spinlock. I've been debugging this looking at the coprocess code and discovered that this is due to the following line in coprocess.cc:

setbuf(d_fp,0); // no buffering please, confuses select

If this is removed, performance in my particular test case goes from 2000qps with powerdns running at about 2000% cpu to 10000qps with powerdns using about 300% cpu.

Obviously the comment implies that this is not a permanent solution, I guess if the timeout is specified as 0 then the select code won't be executed and so you can disable the setbuf easily enough. However perhaps if the timeout is wanted you could set an alarm() rather than using select?
fixes PowerDNS/pdns#692

For the second time when writing a backend I forgot that an ANY query needs to return any SOA data as well. This is because we store our SOA's separately from our other DNS data in order to optimize zone lookups. According to Habbie MyDNS backend has the same bug. The attached patch basically forces an SOA to be included which is actually much more optimal than anything I can do in my backends as I don't have easy access to the knowledge of:

* sd data structure;
* is this query also an SOA

meaning that if I answer it in the backend I have to do a number of additional lookups for information that is already available in the PacketHandler. Additionally, I notice that you are basically doing all the SOA setup anyway if there is anything looking like an SOA entry. So, all this patch does is strip out any SOA entries and then insert one if there should be. This seems to me to both potentially simplify backend code and fix up any user errors more accurately than the current code does.
allow overriding MAKE in regression tests
presumably fix building on os x 10.9, thanks @mactijn
drop unused vars, thanks Morten Stevens
use sed in buildscripts
testbuild spec files for rawhide
move spec files to redhat directory
Merge pull request #1142 from mind04/buildscripts

Buildscripts
add test spec to auth tarball
add test spec to recursor tarball
fix hmac-md5 TSIG key lookup
Merge pull request #1150 from mind04/tsig2

fix hmac-md5 TSIG key lookup
we dont't generate useless NSECs in delegations
add DS at both sides of zone-cut test
auth 3.3.1 changelog draft
Merge pull request #1146 from mind04/buildscripts

add test specs to dist tarball
make sure to run PKG_PROG_PKG_CONFIG before the first PKG_* usage
Merge pull request #1153 from mind04/tests

add DS at both sides of zone-cut test
log nice error message as well as throwing exception