There is an option to enable/disable libsodium via the Visual Studio
UI. This is not practical for command-line usage (via msbuild).
Solution: add configure.bat that searches for libsodium in sibling
directory to libzmq; if it finds it, defines HAVE_LIBSODIUM 1.
This is consistent with zproject, which has the same problem and
is getting the same solution for all dependency resolution on
Windows.
Note that this approach also provides a way to support tweetnacl
via a configure option.
Also, removed duplicate props files and re-copy in configure.bat
as it was an insane nightmare to update these by hand. (and not
clear that they were identical. Now it's forced.)
Of course people still "can" distributed the sources under the
LGPLv3. However we provide COPYING.LESSER with additional grants.
Solution: specify these grants in the header of each source file.
Macro ZMQ_VERSION represents the current version of 0MQ
Macro ZMQ_MAKE_VERSION(major,minor,patch) allows to create
a representation of the specified version.
The versions can be compared using simple <, >, ==, etc.
operators.
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>