fix occasional crash in PulseShapeFitOOTPileupCorrection for zero processed events in a job (as in #6646 )



Initialized data members

the crash in e.g. 106.0 is gone.

The crash in the original code can be more reliably reproduced with the malloc magic

```
export MALLOC_CHECK_=3 
export MALLOC_PERTURB_=$(($RANDOM % 255 + 1))
cmsRunGlibC config.py

```