* libtool.m4 (LD): Append -melf* option to LD on IRIX with GNU ld.

* ltconfig: Handle it.
* ltcf-cxx.sh: Use with_gnu_ld passed as a shell variable instead of
auto-detecting it.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@63148 138bc75d-0d04-0410-961f-82ee72b054a4