Added missing header

Still having errors trying to run in parallel. Changed compiler to mpicc and mpicxx but when I ran it I got:

Running test...
Running test...
Running test...
Running test...
# *** MPI CPU count           : 4
# EqSim condition file: none
# EqSim friction file: test_friction.dat
# EqSim geometry file: test_geometry.dat
# Section params file: none
# Initializing blocks.
# To gracefully quit, create the file quit_vc in the run directory.
# Calculating Greens function with the 2011 Okada class.
# Greens function took 0.0881419 seconds.
# Greens shear matrix takes 25 kilobytes.
# Greens normal matrix takes 25 kilobytes.
# Greens output file: test_greens.h5
# Displaying simulation progress every 30 seconds.
#
# **********************************************
# ***
# *** Blocks                  : 100
# *** Faults                  : 1
# ***                         
# *** Present Time (years)    : 0
# *** Min  cff                : -2.0081e+07
# *** Mean cff                : -1.24006e+07
# *** Max  cff                : -6.366e+06
# ***                         
# To access the HDF5 file during the simulation, pause it 
# by creating the file pause_vc.  Delete the file to resume.
# events        year      minCff[index]      avrCff      maxCff[index]
-------------------------------------------------------
Primary job  terminated normally, but 1 process returned
a non-zero exit code.. Per user-direction, the job has been aborted.
-------------------------------------------------------
--------------------------------------------------------------------------
mpiexec detected that one or more processes exited with non-zero status, thus causing
the job to be terminated. The first process to do so was:

  Process name: [[26708,1],3]
  Exit code:    134
--------------------------------------------------------------------------