Merge branch 'valgrind_errors' of https://github.com/rbberger/lammps into merge-pull-147

From Richard Berger: Fixes the following errors found during Jenkins runs:

prd example: Conditional jump or move depends on uninitialised value(s)
[https://ci.lammps.org/job/coverage/job/mpich-cov-examples-fedora/9/valgrindResult/pid=37296,0x0/]

streitz.ewald example: Memory Leaks (definitely lost)
[https://ci.lammps.org/job/coverage/job/mpich-cov-examples-fedora/9/valgrindResult/pid=37452,0x1/]