fix initialization of local variables in propagation to avoid vagrind warnings

[dan131riley]

PR description:

This PR fixes the initialization of a couple of MPlex arrays allocated on the stack. Previously they were being initialized up to N_proc, but many of the propagation loops go up to NN to aid vectorization. This PR ensures that any MPlex entries past N_proc are set to zero.

PR validation:

Reran valgrind and verified that there were no MkFit warnings.

[slava77]

@dan131riley
the changes look good to me.
Considering the holiday today, I propose to wait til Monday PM in case of comments and then submit to cms-sw

[osschar]

Thanks Dan! Yes, let's push it over to cmssw :)

[dan131riley]

What's the preferred way to push to cmssw--merge here and make the PR from trackreco, and make the PR from my repo?

[slava77]

What's the preferred way to push to cmssw--merge here and make the PR from trackreco, and make the PR from my repo?

the master fork in trackreco/cmssw is not meant for direct merging, only as a reference for preliminary PR reviews.
Please submit the branch used here to cms-sw/cmssw.

[dan131riley]

Submitted as cms-sw#40105

[slava77]

oh, and no need to close here. After the upstream is merged it becomes clear that this one is merged as well (once the master here is synced up).