tipc: add support for address domain suffix

The TIPC protocol bindings in ZeroMQ defaults to a lookup domain
of 1.0.0 to prevent 'closest first' search, and instead always
do round robin if several sockets in the network or node have
the same name published. In retrospect, this might have been a
bad idea because it won't work on standalone configurations.
We solve this by allowing an optional domain suffix to be provided
in the address, and 0.0.0 should be used in that case, or if the
TIPC address range in the cluster configuration is defined to some
other value. Domain suffixes are only relevant for connecting
addresses.
Signed-off-by: Erik Hugne <erik.hugne@gmail.com>

Problem: hint parameter throws unused warning

Fix autotools for static MinGW builds

Problem: sockfd_ parameter throws unused warning

Solution:
Mark it with LIBZMQ_UNUSED macro as per convention.

Solution:
Mark it with LIBZMQ_UNUSED as per our convention.

Revert "problem:Socket try to access closed mutex"

Problem: style/typo issue

Solution:
Fix it.

Problem: Coverage option broken with LLVM GCOV Frontend

Problem: UDP engine code not indented properly [style]

Solution:
This is an issue with the imported Autoconf M4 macro package for standardised
code coverage builds, i.e. using --enable-code-coverage.

The simplest way that I could find is to add a case statement that checks if
the output of running `gcov -version` contains the "LLVM" keyword; if that is
true then do not link with LIBGCOV as its neither required nor supported when
using the GCOV frontend for LLVM; least not on Mac OS X. The case statement
would also be the most portable.

Moreover, using the "-version" argument instead of "-v" seems to be the best
bet as that is supported by the normal GCOV and LLVM GCOV frontend.

Upstream candidate - this solution should be improved by Autoconf M4 macro
overlords and applied to the upstream M4 package; I could not find a suitable
way to detect if LLVM GCOV is being used, except for the solution herein; this
should also work on *BSD too.

Problem: Deploying release artifacts to github is a manual process

Solution: Use travis to deploy these artifacts automatically.

The deployment is triggered by tagging on the zeromq/libzmq repository.
Of the many builds travis is checking only the default one with
libsodium and drafts disabled is used for deployment.

For now the results of `make distcheck` are deployed as well as their
md5 and sha1 hash sums. Further changes may upload a generated
Changelog as well.

Problem: Not all ancillary API methods tested

Solution:
Indent it.

Solution:
- Add file for testing ancillary API methods and any misc internal machinery
- Add tests for zmq_version(3) and zmq_strerror(3)
- Add test file into gitignore, Autotools and CMake build files
- Increase test coverage

Note:
MSVC solution files have not been updated.

problem: sockets are not signed int on Windows

Problem: no backtrace is printed on assert

Solution: clean up and remove it

Solution: add an optional dependency on libunwind, and if present
use it to print the backtrace when zmq_abort is called.