Warnings from AsyncCommPeer.C

With hip clang we get a warning from two lines (849, 850) of AsyncCommPeer.C here https://github.com/LLNL/SAMRAI/blob/master/source/SAMRAI/tbox/AsyncCommPeer.C#L849.

The warning:
warning: cast to 'void *' from smaller integer type 'SAMRAI_MPI::Request' (aka 'int') [-Wint-to-void-pointer-cast]

Inspect source/SAMRAI/tbox/AsyncCommPeer.C at lines 849-850 and reproduce the warning with hip clang. Trace the SAMRAI_MPI::Request cast to void* and verify that the completed change no longer emits the reported -Wint-to-void-pointer-cast warning.

Written by the indexing model from the issue text.