* Background thread scheduling 

- add ZMQ_THREAD_AFFINITY ctx option; set all thread scheduling options
from the context of the secondary thread instead of using the main
process thread context!
- change ZMQ_THREAD_PRIORITY to support setting NICE of the background
thread when using SCHED_OTHER

Solution: Don't unlink file on close

File may not belong to the socket at that point.

Solution: add it to CMake's platform.hpp.in

Solution: Escape quotes in cmake test.

Solution: exclude tweetnacl from coverage

Solution: add it to CMake's platform.hpp.in

Solution: generate list of sources and headers with:

 ls -1 src/*cpp | sort | sed 's|src/\(.*\)|      <File RelativePath="..\\..\\..\\..\\src\\\1" />|g'
 ls -1 src/*hpp | sort | sed 's|src/\(.*\)|      <File RelativePath="..\\..\\..\\..\\src\\\1" />|g'

and add them.

Solution: extracted common base class curve_mechanism_base_t

Solution: run make check with VERBOSE=1

Solution: Move ZAP tests to own file test_security_zap.cpp, move common code to testutil_security.hpp

Solution: created a zap_client_t class, extracted first function send_zap_request from curve_server_t

Solution: Pass along SODIUM_STATIC define if set in CMake config

Linux now supports Virtual Routing and Forwarding (VRF) as per:

https://www.kernel.org/doc/Documentation/networking/vrf.txt

In order for an application to bind or connect to a socket with an
address in a VRF, they need to first bind the socket to the VRF device:

    setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, dev, strlen(dev)+1);

Note "dev" is the VRF device, eg. VRF "blue", rather than an interface
enslaved to the VRF.

Add a new socket option, ZMQ_BINDTODEVICE, to bind a socket to a device.
In general, if a socket is bound to a device, eg. an interface, only
packets received from that particular device are processed by the socket.

If device is a VRF device, then subsequent binds/connects to that socket
use addresses in the VRF routing table.

Solution: if available use the getrandom function as it doesn't
require any synchronization, state or cleanup

Solution: open with O_CLOEXEC if available or set FD_CLOEXEC if not

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

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.

* add define for windows/UWP

* prevent issue with COM references

* gettickcount not available on uwp

* add compiler definitions

* add convenitnece cmake file

* brute force uwp compilation

* fix compiler version

* cosmetics

(msys building is buggy, please be aware, it fails to compile on my
machine) also I modified the buildall.bat/buildbase.bat to use correct
MSVC versions instead of "visual studio 2017"

Fixed path to lib and dll files.

Solution: use pthread API to set the name. For now call every thread
"ZMQ b/g thread". Would be nice to number the I/O threads and name
explicitly the reaper thread, but in reality a bit of internal API
churn would be necessary, so perhaps it's not worth it.
This is useful when debugging a process with many threads.

* cmake WITH_LIBSODIUM option is broken

- Fixed the variable name in platform.hpp.in
- Fixed #if check for randombytes_close() when libsodium is used

* Fixed typo from previous commit

* Reverted compile error fix for randombytes_close()

the root path name specified in this file cause the #2341 problem, the root path name is not need.

Solution: rework the bash test to avoid build failures as intended
and make it an easier one-liner

Solution: use packages on Ubuntu and brews on OSX. The packages and
the brews are always kept up to date, so it's no use to rebuild the
libsodium stable branch manually everytime.

Solution: if available, use eventfd with EFD_CLOEXEC flag to make
the process close the socket on fork+exec

Solution: if available, use epoll_create1 with EPOLL_CLOEXEC flag to
make the process close the socket on fork+exec

Solution: removed Pause