.lib does not get installed when build on Windows with either Cygwin or MSYS2

[ariestav]

Description

When using Cygwin or MSYS2 to build the source, no static library is installed the library directories.

Steps to Reproduce

1. Clone the repository to a directory in the Cygwin or MSYS2 file system
2. Run the build steps to compile source
3. Run make install and note that the .a static library is copied to the /usr/local/lib directory, but no .lib static library is generated or copied to the /usr/local/lib directory.

Expected behavior: [What you expect to happen]
I would expect libhttpserver.lib to be present in /usr/local/lib
Actual behavior: [What actually happens]
The only files that are generated and copied to the /usr/local/lib are the following:

libhttpserver.a
libhttpserver.dll.a
libhttpserver.la

Reproduces how often: [What percentage of the time does it reproduce?]
I can reproduce this 100% in all my tests.

Versions

• OS version (if on linux, the output of "uname -a")
  Windows 10 running either Cygwin or MSYS2

• libhttpserver version (please specify whether compiled or packaged)
  latest on master packaged (building from source)

• libmicrohttpd version (please specify whether compiled or packaged)
  packaged (building from source)

If you have problems during build:

• Compiler version
  gcc 11.3 on Cygwin
  gcc 12.1.0 on MSYS2

[etr]

I suspect this is due to the fact that the classes are not declared with "__declspec( dllexport )" - it should be possible to fix. I'll try to spend some time going through this and see how it works (I am not much of an expert of windows development, sorry)