Eliminate two of the three overloadings of `Scope::MakeDerivedType()`.
Keep the one that has `Category` first because that's the order the
constructor of `DeclTypeSpec` uses.
In `mod-file.cc`, eliminate some calls to `PutLower()`. Symbols and
names are already lower case so they don't need to be converted.
In `modfile03.f90`, move the expected `.mod` file comments to right
after the corresponding modules. That makes it easier to work with.
Original-commit: flang-compiler/f18@86874d9bf8
Reviewed-on: https://github.com/flang-compiler/f18/pull/740
Tree-same-pre-rewrite: false