[modules] Emit the type of the TypeSourceInfo for a DeclaratorDecl (but

[modules] Emit the type of the TypeSourceInfo for a DeclaratorDecl (but
not the corresponding location information) earlier.

We need the type as written in order to properly merge functions with
deduced return types, so we need to load that early. But we don't want
to load the location information early, because that contains
problematic things such as the function parameters.

llvm-svn: 336016