Get the package closer to what upstream intended
    
    We used to move the header files in /usr/include/libev, whereas upstream
    (and other distributions) put them in /usr/include.
    
    This was confusing users of the library, who had to either come up with
    clever tricks to build on Fedora (often as downstream changes to the
    packages in Fedora) or worse, depend on the Fedora-only changes, so that
    the software would not build anywhere else.
    
    However, this means that the /usr/include/event.h file (which we used to
    put in /usr/include/libev/event.h) now conflicts with the one from
    libevent-devel.
    
    To avoid making libev-devel conflict with libevent-devel (which would be
    pretty terrible for users of both libraries, like the libverto
    developers for example), this commit introduces a new
    libev-libevent-devel subpackage just to contain this one header file, so
    that only this subpackage conflicts with libevent-devel.
    
    Given that the point of libev's event.h was to be a compatibility header
    with libevent, this actually makes it easier for users to rely on it.
    
    Finally, the pkgconfig file becomes completely unnecessary. As it was a
    Fedora-specific change that libev upstream rejected several times when
    it was proposed to them, this commit also drops it.
    
    All in all, this should remove user confusion over the Fedora libev
    package, and stop various upstreams from depending on Fedora-specific
    changes.
    
    Note that this should really not be pushed in Fedora <= 20 at this time,
    but only to Rawhide.