chgres_cube should build without -fallow-argument-mismatch compile flag

[edwardhartnett]

chgres_cube should build without -fallow-argument-mismatch compile flag.

See #463 for details.

[kgerheiser]

I made a test program using GCC-10 and MPICH. use mpi doesn't work and throws a type mismatch, but using mpi_f08 works.

program test_mpi_bcast
  use mpi_f08 ! mpi_f08 works
  !use mpi ! this throws a type mismatch error
  use iso_fortran_env, only: real64
  implicit none

  character(len=10)              :: temp_num = 'NA'
  real(real64) :: dx
  integer :: error
  

  call MPI_BCAST(temp_num,10,MPI_CHAR,0,MPI_COMM_WORLD,error)
  call MPI_BCAST(dx,1,MPI_REAL8,0,MPI_COMM_WORLD,error)
  
end program test_mpi_bcast