It fails on some systems.  e.g.
http://git.bind10.isc.org/~tester/builder//BIND10/20120509174501-MacOSX10.6-x86_64-Clang-Static/logs/unittests.out

Conflicts:
	ChangeLog
	src/lib/dhcp/iface_mgr_linux.cc

Conflicts:
	ChangeLog
	src/bin/dhcp4/dhcp4_srv.h
	src/lib/dhcp/libdhcp++.h
	src/lib/dhcp/option.cc
	src/lib/dhcp/option.h
	src/lib/dhcp/option4_addrlst.cc
	src/lib/dhcp/option6_ia.cc
	src/lib/dhcp/option6_iaaddr.h
	src/lib/dhcp/pkt4.h
	src/lib/dhcp/pkt6.cc
	src/lib/dhcp/pkt6.h

also clarified the comment: the previous one didn't make perfect sense in
that if it's really about exception we could have simply used EXCEPT_THROW.

unfortunatelly, we cannot throw here because it's called from the Formatter
destructor.  death tests now work for environments where it previously failed.

- style fixes
- constify (also for replacePlaceholder)
- make sure all parameters are used regardless of ENABLE_LOGGER_CHECKS

this solves various build troubles such as leaving it unused, causing
circular dependcies,  or the use of unnamed namespace in a public header file.

- test prints out information that failed socket binding is ok.
- iface_mgr buffers are no longer static.

Conflicts:
	doc/.gitignore
	src/lib/util/buffer.h

It was temporarily introduced at 1fc79b93 for #1028, but it should have been
cleaned up even before commiting the change.
should be trivial and harmless, so I'm directly commiting the cleanup.

We use anonymous namespace instead of static before a function.

other binaries in log/unittests also need to link to our local libs first