Solution: don't set thread name on Android

Setting a thread name on Android may fail with "permission
denied" error and abort the process due to failed assertion.
Tested on Android 5 and 6 (two phones).
Strangely enough, it only happens on signed APKs and is fine
in debug. Using JeroMQ is not an option as we need TCP keepalive
settings and authentication which JeroMQ doesn't support.

Problem: REP leaves label msgs for dead REQ in pipe

Solution: roll back the pipe if writing messages other than the
first fails in router::xsend. Roll it back also when the pipe is
terminating.
Also add test case that reproduces the memory leak when ran with
valgrind.
Fixes #2567

Revert "Problem: REP leaves label msgs for dead REQ in pipe"

Problem: REP leaves label msgs for dead REQ in pipe

Solution: roll back the pipe if writing messages other than the
first fails in router::xsend.
Also add test case that reproduces the memory leak when ran with
valgrind.
Fixes #2567

Added the license grant for jruffin

license right grant from Leonard Michelet

Relicensing grant from rotty

Problem: not using official api FD_ZERO to init fd_set

solution: fix it

In particular, on Windows, using FD_ZERO is much more efficient than
zeroing out the whole structure.

Problems: cannot use wildcard port with source address, tests bind to hardcoded TCP ports, ASAN CI run could use some improvements

Grant permission to relicense to MPL

Solution: add Ubuntu toolchain PPA and use GCC 6

Solution: pass -g so that valgrind/asan can print useful backtraces

Solution: import better solution from zproject and add a new autoconf
option

Solution: mark it as XFAIL. We tried many times to tweak the system
settings from the CI script but it still fails.

Solution: run make with -j5, as now the tests support it.

Solution: don't, libzmq's CI tests are not responsible for testing
libsodium stable releases. Save some time in the CI.

Solution: use either a wildcard IPC, or where the codepath needs to
be tested a file named after the test, so that it is unique and there
is no clash on the filesystem, allowing parallel test runs.

Solution: use ZMQ_LAST_ENDPOINT in most places. This alllows running
tests in paralle, and on over-booked shared machines where many of
the ports would be already in use.
Keep 3 tests with an hardcoded port, as there are some code paths that
require it (eg: connect before bind), but list those ports in
tests/testutil.hpp as macros so that they do not overlap and still
allow parallel runs.

These changes were inspired by a patch uploaded to Ubuntu by the
package maintainer, Steve Langasek <steve.langasek@ubuntu.com>.
Thank you Steve!

RELICENSE: Grant from michicc

Solution: fix TCP endpoint parsing to allow
tcp://127.0.0.1:*;127.0.0.1:1000

Problem: no way to deploy releases to OBS

Solution: add new tokens to .travis.yml and change ci_deploy.sh
script to use Github APIs to create a temporary branch at the tag,
and the OBS APIs to trigger a source service run in the stable and
draft release projects:
network:messaging:zeromq:release-stable
network:messaging:zeromq:release-draft

The branch hack is unfortunately necessary as it is not possible to
modify OBS sources with the token APIs, and it is also not possible
to automatically fetch the latest tag in the service files.
The temporary branch is immediately deleted.

Problem: RPM build fails due to ignored zmq_gssapi.7

Solution: a new option has been added to the tar_scm service, so use
it to set the version to last_tag+git<last commit date> which is more
useful.
Unfortunately it's not possible to set it to the current version as
set in the header files, as it's not possible to parse files, only
commit ids, dates and git tags. But it's a step forward.

Solution: use wildcard to pick up manpages in the spec file

Problem: new zmq_poller used by zmq_poll without DRAFTs

Solution: do not define ZMQ_HAVE_POLLER in src/zmq_drafts.h otherwise
src/zmq.cpp will implement zmq_poll using the new poller classes.
Same for ZMQ_HAVE_TIMERS, even though it has no internal effect, but
to be safe against future development.

Fix WITH_DOC

add simple GSSAPI test for make check

Problem: there is no test coverage for GSSAPI.

Solution: add a test structured like the CURVE test.

The test is not built if libzmq is not configured with
--with-libgssapi_krb5. It will report SKIPPED status
if the required environment is missing (see below).

Environment:  KRB5_KTNAME and KRB5_CLIENT_KTNAME
environment variables must point to a keytab file
containing creds for a host-based test principal
(see comment at top of source for details).
Kerberos must be configured and a KDC containing the
test principal must be running, otherwise the test
will fail/hang.

N.B. For now, the test must use the same principal for
both client and server roles because it seems impossible
to set them to different principals when they are
threads in the same process.  Once one principal is
cached in credential cache, attempts to acquire creds
for a different "desired name" seem to be ignored and
the cached principal is used instead.