Many ports (m32r, microblaze, mips, parisc, score, and sparc) use
functionally identical copies of various GCC library routine files,
which came up as we were submitting the RISC-V port (which also uses
some of these).

This patch adds a new copy of these library routine files, which are
functionally identical to the various other copies.  These are
availiable via Kconfig as CONFIG_GENERIC_$ROUTINE, which currently isn't
used anywhere.
Reviewed-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NPalmer Dabbelt <palmer@dabbelt.com>