minor bug

[yoonbo]

Line 160 of lib/lattice/spinor_halo_qmp.cpp in devel branch, the destructor SpinorHaloCB::~SpinorHaloCB() is calling

QMP_free_msghandle()

However, at the end of Chroma run, the destructor is invoked after some finalize(), which includes MPI_FINALIZE, is called, so it yields the following error message:

error: In file qmp/lib/QMP_mem.c, function QMP_free_msghandle, line 293:
error: assert failed QMP_machine->inited==QMP_TRUE
error: abort: 1
*** The MPI_Abort() function was called after MPI_FINALIZE was invoked.
*** This is disallowed by the MPI standard.
*** Your MPI job will now abort.