In this assignment, you will modify your arguement broadcast routine to
communicate different datatypes with a single MPI broadcast (MPI_Bcast) call.
Have your program read an integer and a double-precision value from standard
input (from process 0, as before), and communicate this to all of the other
processes with an MPI_Bcast call.  Use MPI datatypes.
<P>
Have all processes exit when a negative integer is read.
