hpcprof-mpi: Fix bug computing thread-local metric-db.
hpcprof-mpi: Fix bug computing thread-local metric-db.

[hpcprof-mpi]makeThreadMetrics_Lcl(): Make sure to (re)initialize a
CCT node's metric vector before reading the next thread-local profile.


HPCToolkit/hpctoolkit,zcth428/hpctoolkit,zcth428/hpctoolkit111,zcth428/hpctoolkit,zcth428/hpctoolkit111,zcth428/hpctoolkit,zcth428/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,zcth428/hpctoolkit111,HPCToolkit/hpctoolkit,zcth428/hpctoolkit111,zcth428/hpctoolkit,zcth428/hpctoolkit111