Log Message:
Update of devel/ocaml-lwt to its newest version, 2.4.2. Changes include:

2.4.2
* fix the stub for Lwt_unix.readdir
* change the default method for Lwt_glib.install (use the glib main loop by
  default: more portable)
* ignore invalid file descriptors returned by glib (like the emulation of
  select in glib does)
* use environment variables in discover.ml - use LIBRARY_PATH and
  C_INCLUDE_PATH for searching headers - allow to pass flags for a library
	in <LIB>_CLFAGS and <LIB>_LIBS
* add Lwt_unix.on_signal_full

2.4.1
* Add Lwt_stream.on_terminate
* Fix Lwt_gc
* Fix stubs for get_credentials on *BSD