updated CTS_BUF_DISTANCE handling + AT genMetric.py call fix

[jeffng-or]

Merge of #3106 and part of #3108.

• Fixes CTS_BUF_DISTANCE flow variable handling
• Fixed call to genMetrics.py in AutoTuner

@luarss , @vvbandeira , @arthurjolo FYI.

[jeffng-or]

@luarss , @vvbandeira FYI. I removed sky130hd gcd from the sample iteration test because it continually fails with sample == 1. The AT can't find a successful run with only one sample, so it's a fragile test.

[luarss]

Yep that is fine - I have pushed a fix in #3025 to be more tolerant of parameter tuning failure (error code 16), so that is a more long term fix

[jeffng-or]

@luarss , @vvbandeira FYI. I removed sky130hd gcd from the sample iteration test because it continually fails with sample == 1. The AT can't find a successful run with only one sample, so it's a fragile test.

It looks like the failure is a seg fault in DPL. I'm able to repro locally, so will file an issue. Closing this PR and will send up a separate PR for the genMetrics.py fix, so that we can get the AT working again.