Synchronize with recent CoreMark

[jserv]

It has been a long time since last source adaptation of eembc/coremark. Directory sw/coremark contains an old copy, and it would be nice to use git submodule to synchronize with recent CoreMark instead of C source file duplications.

[kuopinghsu]

CoreMark hasn't been updated for a long time, the most recent change is to fix some typos. I think I will keep a copy to make some modifications.

[kuopinghsu]

No plans to sync with coremark's master branch