Comment out nan warning message - fitacf3

[ksterne]

As we discussed in the Nov. 2025 Data Analysis Working Group meeting, some of the regenerated cve, cvw have -nan values in the acfd and other data arrays. These values cause the current fitacf3 processing to output a lot of warning messages about calculated values that are also -nan.

This pull request comments out the check for -nan and the subsequent warning print statement. An example file which this fixes is the 20201231.0601.00.cvw.rawacf.bz2 file.

[pasha-ponomarenko]

I guess there is nothing to test here...

[ksterne]

If this looks good and you trust the compilation test or have tested a compilation yourself, that should work. I could also supply the file and instructions to test if that would be helpful.

[egthomas]

What about addressing the root cause of fitacf3 trying to fit data with nave = 0 (as mentioned in #650)?

[ksterne]

I agree the root cause is good to check on, but this pull request is a quick reaction to the offending code from what we discussed at the last meeting. I'm sure we could add a check for nave to fitacf3 in another pull request.