* cmake: remove mscclpp patch after build is complete
To enable mscclpp in cpx mode, a patch cpx.patch needs to be applied.
This patch can be removed after building is done. This helps with the
build process the following time.
* Use read-based mscclpp allreduce from rccl
MSCCLPP by default uses remote write in the allreduce kernel for
large (> 1MB) messages. This PR adds an allreduce kernel that uses
remote read. It needs the users to use an environment variable
MSCCLPP_READ_ALLRED=1.
[ROCm/rccl commit: 4d68751ce1]
Nusrat Islam