* doc/libtool.texi (libltdl): list supported dlopen mechanisms,

* doc/libtool.texi (libltdl): list supported dlopen mechanisms,
  added function lt_dlopenext(), removed reference to
  LTDL_PRELOADED_SYMBOLS in LTDL_SET_PRELOADED_SYMBOLS
* libltdl/ltdl.c: partially reverted Alexandre's dynamic string
  allocation change (it was not necessary and the code was unreadable),
  cleanups, removed usr_search_path_size, renamed usr_search_path
  to user_search_path, in find_module() also check for moved
  modules, merged find_file() and find_library(),
  added lt_dlopenext(), in lt_dladdsearchdir() no longer reset
  the search path if 'search_dir' == NULL and don't use realloc()
  (might not be available on all platforms),
  removed __P((void)) in the declaration of lt_dlgetsearchpath()
* libltdl/ltdl.h: added lt_dlopenext()
* ltconfig.in: AIX archive commands were broken,
  fixed a MAJOR bug in global_symbol_pipe which caused
  "demo-shared.test;demo-make.test" to fail (libtool must not extract
  undefined symbols of libraries, i.e. symcode must not contain 'U')
* tests/Makefile.am (clean-local): "make distclean" in cdemo, too