Unnecessary static linking of zlib in cmake infrastructure

[pmetzger]

While packaging Open SIMH for macports, it was discovered that dep-locate.cmake does set(ZLIB_USE_STATIC_LIBS ON), which forces the use of a statically linked system zlib. Unless this is actually necessary, it should be removed. We've added a patchfile to do that, and it seems to cause no harm.

[bscottm]

@pmetzger: That's intentional. @pkoning2 and a few other contributors wanted simulators to be statically linked. That's probably more of a Windows-related issue -- you can't just copy the simulator over to another place without also copying the dynamic libraries -- and less of an issue on other platforms. It's not a heavy lift to make that static linking Windows-only.

I can set up a branch to make static linking a Windows-only feature and see how it works out for Linux and macOS. Willing to test?

[bscottm]

@pmetzger: Looks like the only change will be to dep-locate.cmake and test if CMake is on Windows. All of the other places already have that test (i.e., only static link on Windows.)

[pmetzger]

I think that setting this windows only would work well. Note that essentially all other dynamic libraries that SIMH depends on are dynamically linked; only zlib was being forcibly statically linked.