stage2: get Module and Sema compiling again

There are some `@panic("TODO")` in there but I'm trying to get the
branch to the point where collaborators can jump in.

Next is to repair the seam between LazySrcLoc and codegen's expected
absolute file offsets.
b2682237dbAndrew Kelley committed on 3/19/2021, 5:19:28 AMparentf5aca4a
9 files changedLine totals unavailable