/*D
   MPI_Aint_diff - Returns the difference between addr1 and addr2

Synopsis:
.vb
MPI_Aint MPI_Aint_diff(MPI_Aint addr1, MPI_Aint addr2)
.ve

Input Parameters:
+ addr1 - minuend address (integer)
- addr2 - subtrahend address (integer)

Notes:
MPI_Aint_diff produces a new MPI_Aint value that is equivalent to the difference
between addr1 and addr2 arguments, where addr1 and addr2 represent addresses
returned by calls to MPI_GET_ADDRESS. The resulting address is valid only at the
process that generated addr1 and addr2, and addr1 and addr2 must correspond to
locations in the same object in the same process. The difference is calculated
in a manner that results the signed difference from addr1 to addr2, as if the
process that originally produced the addresses had called
.vb
    (char *) addr1 - (char *) addr2
.ve
on the addresses initially passed to MPI_GET_ADDRESS.

.seealso: MPI_Aint_add
D*/

