Add a Barrelfish extension to RCCE: If 0 is passed as reference clock commandline parameter, automatically determine reference clock speed.
Add a Barrelfish extension to RCCE: If 0 is passed as reference clock
commandline parameter, automatically determine reference clock speed.

This is helpful for automating RCCE benchmark runs using the harness.
Previously, we used a fixed, fake reference clock value of 1 GHz, which made
all automatically generated benchmark results scaled from wall clock
time.

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