swift234

[func-sig-opts] Track the original index of the argument in ArgumentDescriptor and use it to create fix lifetimes and releases.

This means that:

1. I can make the ConsumedArgToEpilogueReleaseMatcher a local variable
instead of being on the FunctionAnalyzer class. This will be done in a
latter commit.

2. When I SROA arguments, I always put the fix_lifetime, release_value
on the correct argument by reusing old values. In the case of creating
the thunk, I use the thunks arguments which are the same as the old args
and I use the argument list of the old ApplyInst in the caller functions
before I delete the old ApplyInst. This means that when I SROA the
arguments of a function, the @owned => @guaranteed argument will work
without any changes.

Swift SVN r23499