Enable GDA+IPC (#249)

* Enable GDA+IPC
Fix ROCSHMEM_DISABLE_IPC for both RO and GDA

* add more functionality to bootstrap class

we need a few more functions in the boostrap class to be able to fully
handle the rocshmem requirements:
 - add a function to return the list of local ranks
 - provide a groupAllgather operation which takes a vector of ranks
   participating
 - provide a groupAlltoall operation which takes a vector of ranks
   participating

Also, update the functionality of the gda-Alltoall and gda-Allreduce
operations to take advantage of these functions.

* ipc_policy adapted to use bootstrap groupallgather

* bugfix: there was a mistake in computing sendto in groupallgather

* bugfix: shm_size and shm_rank were set in a local variable rather than
the class member

* mpi-bootstrap: remove an unecessary allgather

---------

Co-authored-by: Edgar Gabriel <Edgar.Gabriel@amd.com>

src/reverse_offload/context_ro_host.cpp

@@ -44,17 +44,16 @@ __host__ ROHostContext::ROHostContext(Backend *backend, long options)
 
   int *pes_with_ipc_avail = new int[backend->ipcImpl.shm_size];
   char** ipc_bases = new char*[b->ipcImpl.shm_size];
-
-  CHECK_HIP(hipMemcpy(pes_with_ipc_avail,
+  if (backend->ipcImpl.pes_with_ipc_avail != nullptr) {
+    CHECK_HIP(hipMemcpy(pes_with_ipc_avail,
                   backend->ipcImpl.pes_with_ipc_avail,
                   backend->ipcImpl.shm_size * sizeof(int),
                   hipMemcpyDeviceToHost));
-
-  CHECK_HIP(hipMemcpy(ipc_bases,
+    CHECK_HIP(hipMemcpy(ipc_bases,
                   backend->ipcImpl.ipc_bases,
                   backend->ipcImpl.shm_size * sizeof(char *),
                   hipMemcpyDeviceToHost));
-
+  }
   ipcImpl_.pes_with_ipc_avail = pes_with_ipc_avail;
   ipcImpl_.ipc_bases = ipc_bases;
   ipcImpl_.shm_size = backend->ipcImpl.shm_size;
@@ -62,9 +61,9 @@ __host__ ROHostContext::ROHostContext(Backend *backend, long options)
 }
 
 __host__ ROHostContext::~ROHostContext() {
-  // host_interface->release_window_context(context_window_info);
   delete[] ipcImpl_.pes_with_ipc_avail;
   delete[] ipcImpl_.ipc_bases;
+  // host_interface->release_window_context(context_window_info);
 }
 
 __host__ void ROHostContext::putmem_nbi(void *dest, const void *source,