Remove bottleneck in validation

[luukp]

Even with debugLibrary not enabled ValueStr is calculated in this call, which causes significant bottlenecks in validation.

All other calls to DbgPrint already use ValueStrDebug to avoid formatting string output that won't ever be used.

In my test use case this changed performance from approximately 80s to 40ms.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

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[coveralls]

coverage: 89.522%. remained the same when pulling acc4c17 on luukp:master into 9e37362 on openconfig:master.

[robshakir]

Hi -- please can you sign the Google CLA at https://cla.developers.google.com/ such that we can accept the change here? Thanks!

[luukp]

Hi, I am working on it - just discussing whether to use the individual CLA or the employer CLA with management.

[robshakir]

Thanks! Keen to merge (and very grateful for) these kind of performance improvements. Please let us know if there's anything that we can help with w.r.t the CLA.

[luukp]

Hi, the CLA is sorted now.

[wenovus]

Thanks Luuk, LGTM