This patch does the following:
- Corrects include paths.
- Remove duplicated symbols from the linker version script. Bfd linker is permissive but lld issues an error.
- Correctly selects the unordered_map definition namespace.
- Defines barriers for mips/arm using strongest CPU barriers.
RISC-V was not handled but the logistics required to make it included into make universe on the machine is not worth the efforts.