This directory builds a verto library with only a private built-in
module, for use when the system has no installed verto library.  The
bundled verto cannot dynamically load modules.  From the upstream
libverto, we take only verto.c and verto-libev.c, and we only build
the former; the latter is stored here for comparison purposes.  We use
a stub implementation of module.c to disable dynamic loading support.

This private module uses an embedded libev with renamed symbols (so we
don't leak libev symbols into the namespace on platforms where we
can't control the export list).  libev has built-in support for this
kind of embedding, so we don't have to modify the libev sources.
Following libev's documentation, the following files have been copied
from the ev sources:

  ev.h
  ev_vars.h
  ev_wrap.h
  ev.c
  ev_select.c
  ev_poll.c
  ev_win32.c
  Symbols.ev

(Symbols.ev wasn't included in the 4.04 tar file due to an oversight,
so it is taken from the appropriate tag in libev's source repository.)

To rename the exported symbols, we create rename.h from Symbols.ev.
We also use Symbols.ev to construct the library export list.
(Renaming libev's symbols would be unnecessary if libev's embedding
had support for making its API symbols static, but it currently does
not.)  The source file verto-k5ev.c wraps ev.c with appropriate
embedding defines, and then defines the libverto module functions
using the slightly modified contents of libverto's verto-libev.c.  The
resulting module table is embedded into verto.c using the
BUILTIN_MODULE define.

The libverto and libev upstream project pages are at:

  https://github.com/latchset/libverto/
  http://software.schmorp.de/pkg/libev.html