* NEWS: Updated.

* NEWS: Updated.
* doc/libtool.texi (Thread Safety in libltdl): New node describing
the  application the new MT API.
* libltdl/ltdl.h: Prototypes.
* libltdl/ltdl.c: Use these functions throughout the rest of
the file to provide thread locking.
(lt_dlmutex_register): New function to set callbacks for
multi-threaded calls into libltdl.
(lt_dl_mutex_lock): Type of a locking callback function.
(lt_dl_mutex_lock): Type of an unlocking callback function.
(lt_dl_mutex_seterror): Type of a callback function to save the
last libltdl error message in thread local storage.
(lt_dl_mutex_geterror): Type of a callback function to retrieve
the last saved error message from thread local storage.

* ltconfig.in: Likewise.
* ltcf-c.sh: Likewise.
* ltcf-cxx.sh: Likewise.
* ltcf-gcj.sh: Likewise.