Rewrite fcntl support.
Rewrite fcntl support.

* Remove fcntl table and special handlers for F_GET/SETFL.

* Add instead a single fcntl functions, with constants for all the
  standard commands except for the file-locking commands (this would
  require support for struct flock).

zevv/luaposix,snegovick/luaposix,jimmyharris/luaposix,ardje/luaposix,zevv/luaposix,rrthomas/luaposix,luaposix/luaposix,ardje/luaposix,snegovick/luaposix,rrthomas/luaposix,jimmyharris/luaposix