PATCH ld for AIX5 on IA-64

[Timothy Wall]

ld/Makefile.am: Add AIX emulation.
ld/Makefile.in: Regenerate.
ld/configure.host:  Add ia64-*-aix* configuration.
ld/configure.tgt: Ditto.
ld/emulparams/elf64_aix.sh: New.  Settings for AIX output files.
ld/testsuite/ld-bootstrap/bootstrap.exp: Exclude AIX/IA-64 from usual
AIX tests.