* gcc.c: Add linker spec.
(link_command_spec): Use %(linker) instead of ld.
(main): If collect2 is requested as the linker, see if it exists;
if not, use ld instead.
* Makefile.in (USE_COLLECT2): It's named collect2 now, not ld.
(ld:) Deleted.
(install-collect2): Install as collect2, not ld.
* configure.in(will_use_collect2): It's named collect2 now.
* collect2: Remove checks to see if we were invoked recursively.
(collect_execute): Use _spawnvp under cygwin32.