AIX collect2

[Tom Rix]

This patch improves  64 bit linking and static constructors/ destructors
on AIX.

For 64 bit linking the environmental variable LD_EMULATION is set to
aixppc64.  This was done instead of mapping -b64 to -maixppc64, because
doing so would break native linking.

On AIX static constuctors/desctructors are handled with a special symbol
__rtinit.   This is -binitfini:<init func>:<fini func>  on the native
linker.  This symbol is now emitted.

The usual testsuite does not explicitly look for the __rtinit symbol.
I have created a test.  Since it is device dependent, I placed it in a
new dir.  g++.dd/rs6000.

Tom

--
Tom Rix
GCC Engineer
trix@redhat.com
256.704.9201