Reimplement sys_errlist[] so that it works on sparc, alpha, and mips.

Reimplement sys_errlist[] so that it works on sparc, alpha, and mips.
In my opinion, this is a complete waste of good memory and is only
done to avoid the anticipated whining by people who think this libary
is named uCglibc.  At some point this may become a configurable option.
And even then, it may not be available in all configs... for instance
when system error messages become locale-dependent.