multilib dirs and ld.so

[Peter O'Gorman]

Hi,
Albert pointed out to me yesterday that while, with 1.5.24 we now add
the correct directories to sys_lib_search_path_spec, they do not get
added to sys_lib_dlsearch_path_spec, resulting in libtool putting, for
example, /usr/lib64 in RPATH.

Red Hat have a patch for this, but it is specific to redhat:
http://www.redhat.com/archives/fedora-extras-commits/2007-July/msg04567.html

So, it looks like we need to revisit the methods of calculating
sys_lib_dlsearch_path_spec in a distro independent fashion.

The proposals so far:
http://lists.gnu.org/archive/html/libtool/2007-06/msg00025.html

The only worries I have with Olly's proposal are that it can be slow
(but it is only run once at configure time, so hmm) and that I am not
convinced that it outputs the directories in the order that ld.so
searches.

Peter