Much as we have tried not to make it the callers' responsibility

Much as we have tried not to make it the callers' responsibility
to maintain an lt_dlrealloc function pointer, it is too difficult
to implement realloc as malloc/memcpy/free without knowing the
size of the original block.  rpl_realloc has been deprecated since
2002-10-30, but kaffe has real failures with that so it's time to
bite the bullet.  Caller gets to maintain lt_dlrealloc:

* NEWS (1.5.1): Updated.
* libltdl/ltdl.c (LT_DLREALLOC): Use lt_dlrealloc so the user can
update the function pointer to match lt_dlmalloc.
(lt_emalloc): Use lt_dlrealloc rather than hardcoding realloc.
* doc/libtool.texi (Libltdl interface): Describe lt_dlrealloc now
that it too has become part of the exported interface to libltdl.