Reads from a binary file.
comm - the MPI communicator
fd - the file descriptor
num - the maximum number of items to read
type - the type of items to read (
data - the buffer
count - the number of items read, optional
If count is not provided and the number of items read is less than the maximum number of items to read, then this routine errors.
PetscBinarySynchronizedRead() uses byte swapping to work on all machines.
Integers are stored on the file as 32 long, regardless of whether
they are stored in the machine as 32 or 64, this means the same
binary file may be read on any machine.