Those files are autogenerated on Windows builds.

On Windows during compile time it is not only target .dll that is needed
to link to a DSO, but also corresponding .lib and .exp files. And if the
.lib file cannot be found linking fails. On regular install for a DSO X we are
currently installing all X.dll, X.lib and X.exp, but for in-place builds we
copy only X.dll into intree without X.lib and the rest.

This leads to build failures when an external project tries to link to a DSO
from `pip install -e` installed project.  Below is, for example, how it looks
for the link failure of added example/project2 to dsodemo.lib.demo without the fix:

```console
(1.wenv) Z:\home\kirr\src\tools\go\pygo-win\setuptools_dso\example\project2>python setup.py build_ext -i
running build_ext
building 'use_dsodemo.ext' extension
Z:\home\kirr\src\tools\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\bin\Hostx64\x64\cl.exe /c /nologo /Od /W3 /GL /DNDEBUG /MD -I../src -IZ:\ho
me\kirr\src\tools\go\pygo-win\1.wenv\include "-IC:\Program Files\Python310\include" "-IC:\Program Files\Python310\Include" -Iz:\home\kirr\src\tools
\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\include -Iz:\home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\include\10.0.22000.0\shared -Iz:\
home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\include\10.0.22000.0\ucrt -Iz:\home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\include\10.0.2
2000.0\um -Iz:\home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\include\10.0.22000.0\winrt /EHsc /Tpsrc/use_dsodemo/ext.cpp /Fobuild\temp.win-amd
64-cpython-310\Release\src/use_dsodemo/ext.obj
ext.cpp

creating Z:\home\kirr\src\tools\go\pygo-win\setuptools_dso\example\project2\build\lib.win-amd64-cpython-310
creating Z:\home\kirr\src\tools\go\pygo-win\setuptools_dso\example\project2\build\lib.win-amd64-cpython-310\use_dsodemo
Z:\home\kirr\src\tools\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\bin\Hostx64\x64\link.exe /nologo /INCREMENTAL:NO /LTCG /DLL /MANIFEST:EMBED
,ID=2 /MANIFESTUAC:NO /LIBPATH:Z:\home\kirr\src\tools\go\pygo-win\setuptools_dso\example\src\dsodemo\lib "/LIBPATH:C:\Program Files\Python310\libs"
 "/LIBPATH:C:\Program Files\Python310" /LIBPATH:z:\home\kirr\src\tools\go\pygo-win\BuildTools\vc\tools\msvc\14.35.32215\lib\x64 /LIBPATH:z:\home\ki
rr\src\tools\go\pygo-win\BuildTools\kits\10\lib\10.0.22000.0\ucrt\x64 /LIBPATH:z:\home\kirr\src\tools\go\pygo-win\BuildTools\kits\10\lib\10.0.22000
.0\um\x64 demo.lib /EXPORT:PyInit_ext build\temp.win-amd64-cpython-310\Release\src/use_dsodemo/ext.obj /OUT:build\lib.win-amd64-cpython-310\use_dso
demo\ext.cp310-win_amd64.pyd /IMPLIB:build\temp.win-amd64-cpython-310\Release\src/use_dsodemo\ext.cp310-win_amd64.lib

LINK : fatal error LNK1181: cannot open input file 'demo.lib'
error: command 'Z:\\home\\kirr\\src\\tools\\go\\pygo-win\\BuildTools\\vc\\tools\\msvc\\14.35.32215\\bin\\Hostx64\\x64\\link.exe' failed with exit code 1181
```

This fix is simple: on inplace build copy into intree not only .dll but
also .lib and .exp files.

In the next patch we will need to use C-API provided by dsodemo.lib.demo
from external package.

with MSVC, _fix_compile_args(include_dirs=None)
appends to self.include_dirs  on each call.

Shouldn't be modified, but hard to tell if it is.