infer results of a pattern from implicit defs. This allows you to do something

infer results of a pattern from implicit defs.  This allows you to do something
like this:

 def : Pat<(add ...),
           (FOOINST)>;

When fooinst only has a single implicit def (e.g. to R1).  This will be handled
as if written as (set R1, (FOOINST ...))

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98897 91177308-0d34-0410-b5e6-96231b3b80d8