Only include core functions in libgphobo2.so.

Only include core functions in libgphobo2.so.

Only etc, gcc, internal are now included in the build, not std.

This is because the .so file is needed at runtime, so you need to be able to
get it without downloading the whole compiler. Therefore, it should come with
the (much smaller) Delight standard library. So the plan is:

- libgphobo2.so contains only things that must be built with the compiler.
- libdlt contains the rest.
- libdlt is bundled with a copy of libgphobo2.so.

There are therefore two copies of libgphobo2.so, which is why it needs to be as
small as possible.