Ref.: https://github.com/naelstrof/slop/issues/86#issuecomment-328479278

It was moved to slop subdirectoty in attempt to get rid of rpmlint
warning concerning non-standard soname:  this would make 'libslopy.so' a
"private" library, for which naming is not mandatory.

However, this actually breaks slop binary!

Turns out there's no way around it.  What we could do is, in order of
preference:

 1. Solve naming issue with upstream.

 2. Just call it libslopy.so.1.

 3. Use wrapper to add %{_libdir}/slop to LD_LIBRARY_PATH

(The last thing seems really like a too hacky for such simple utility.)

Since libslopy is considered private, there should not be need for
header file.