Now instead of changing it to the new format and then linking, it just
handles the old format while copying it over.
The main differences are:
* There is no rauw in the source module.
* An old format input is always upgraded.
The first item helps with having a sane API that passes in a GV list to
the linker.
The second one is a small step in deprecating the old format.
llvm-svn: 254907
