libltdl crashes under Solaris LP64 64-bit model

[Bob Friesenhahn]

Under SPARC Solaris, libltdl crashes when compiled for the 64-bit
addressing model.  I received these words from the ImageMagick
developer who is flushing out 64-bit related bugs:

The bug is in ltdl and may be related to 64-bit or perhaps not.  I added
(void) lt_dlopen("tiff.la") as the very first call of convert.c and got
a fault:

detected a multithreaded program
address@hidden (address@hidden) terminated by signal BUS (invalid address 
alignment)
Current function is rpl_argz_create_sep (optimized)
  521     *pargz_len = argz_len;
(/opt/SUNWspro/bin/../WS6U1/bin/sparcv9/dbx) where                           
current thread: address@hidden
=>[1] rpl_argz_create_sep(str = ???, delim = ???, pargz = ???, pargz_len = ???)
(optimized), at 0xffffffff7f165258 (line ~521) in "ltdl.c"
  [2] foreach_dirinpath(search_path = ???, base_name = ???, func = ???, data1 =
???, data2 = ???) (optimized), at 0xffffffff7f167cec (line ~2184) in "ltdl.c"
  [3] try_dlopen(phandle = ???, filename = ???) (optimized), at
0xffffffff7f168c44 (line ~2688) in "ltdl.c"
  [4] lt_dlopen(filename = ???) (optimized), at 0xffffffff7f169f54 (line ~2919)
in "ltdl.c"
  [5] main(argc = ???, argv = ???) (optimized), at 0x100003c7c (line ~449) in
"convert.c"