Windows cross-build of libzip 1.4.0 fails

[Benjamin Gilbert <bgilbert%backtick.net@localhost>]

Hi,

libzip 1.4.0 has several problems cross-building for Windows from Linux with MinGW-w64:

1. regress/malloc.c #includes dlfcn.h, which doesn't exist on Windows.  The Autotools infrastructure did not attempt to build malloc.c on Windows, but regress/CMakeLists.txt does not appear to contain any such exclusion.

2. ziptool is built for the target system, but "make" attempts to run it on the build system to create test data.  Autotools did not do this if "make check" was not run.

3. nonrandomopentest is once again being built, and this time failing with a different error:

CMakeFiles/nonrandomopentest.dir/objects.a(nonrandomopentest.c.obj): In function `main':
[...]/libzip-1.4.0/regress/nonrandomopentest.c:45: undefined reference to `zip_random'

That makes sense, as zip_random is not declared dllexport.

--Benjamin Gilbert