Fix a Clang warning on OSX

In file included from unix_semaphore.cc:24:
./utility.hh:53:10: warning: private field 'm_pSemaphore' is not used
[-Wunused-private-field]
  sem_t *m_pSemaphore;
           ^
OSX 10.9 now has IP_PKTINFO
Document optional trace-regex in rec_control help

To clear tracing, rec_control trage-regex should be called without a regex parameter. Document in rec_control help.
Manpage: document all known options for rec_control

The rec_control manpage was missing a number of options that were mentioned in rec_control help. Rectified.
Manpage: small parameter syntax consistency

Add <> around all parameters.
Small typo fix for set-minimum-ttl
Merge pull request #1516 from sid3windr/master

Manpage and help output updates for rec_control
update recursor build instructions
add default for empty value to asNum(), and use a value of 1 for all thread settings in auth
upgrade notes, module-dir location switched form LIBDIR to PKGLIBDIR
don't add superfluous nsec3 for old bind
allow building of gpgsql/lua/mydnsbackend, plus yahttp, when boost is in a non-standard location. Fixes #1521
allow building of db2/goracle/ldap/opendbx/oracle backends (untested) plus tinydnsbackend (tested), when boost is in a non-standard location
Merge pull request #1518 from mind04/receiver-threads

add default for empty value to asNum(), and use a value of 1 for all thr...
Merge pull request #1525 from mind04/libdir

upgrade notes, module-dir location switched form LIBDIR to PKGLIBDIR
Merge pull request #1526 from mind04/no-flu

don't add superfluous nsec3 for old bind
fix typo, thanks Marek Kozlovsky
limit AXFR to loopback by default, closes #1287
oops
detect presense of tm_gmtoff in tm structure and add conditional build logic in yahttp