[testsuite][M680x0] Add CycleTimer implementation for M68K architecture

This is a cherrypick of the upstream fix commit ffe1342 onto
the google benchmark within llvm-test-suite.
This adds CycleTimer implementation for M680x0, and simply
uses `gettimeofday` to implement, same as MIPS.

Differential Review: https://reviews.llvm.org/D89011
4 files changed