This will override the existing winsymlinks setting. nativestrict
will cause ln to fail if it's unable to create a native symlink.
Native symlinks are required for the windows dll loader to find the
libraries.
This script is also used for cross-mingw, but setting CYGWIN
shouldn't cause a problem.
For every *.{exe,dll} in $output/bin/ we try to find all (potential)
transitive dependencies and symlink those DLLs into $output/bin
so they are found on invocation.
(DLLs are first searched in the directory of the running exe file.)
The links are relative, so relocating whole /nix/store won't break them.
The hook is activated on cygwin and when cross-compiling to mingw.
