OK, after checking the backwards compatibility code on X86 and the new code

OK, after checking the backwards compatibility code on X86 and the new code
path on alpha, now has come the time for new vararg support.  So, with out
further ado, I revert behavior back a couple of years!

Well, ok, I lied.  A few more notes.

First, the Simple ISels cannot be expected to work any longer, but they
should still compile

Second, there are likely some bugs to track down once the nightly testers
start with this.

Third, the initial patch doesn't include sparcv9, but I'll do that today.

Forth, subsequent patches won't bother being long winded.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22251 91177308-0d34-0410-b5e6-96231b3b80d8