Cleanup unused code in repository (#75)

* Remove unused forward_list

* Remove unused __read_clock function

* Replace wallClk code with hip function

* Remove unused unit test for ipc

* Remove slab heap

* Remove unused EBO spinlock

[ROCm/rocshmem commit: 0fd628458c]

projects/rocshmem/src/context.hpp

@@ -30,7 +30,6 @@
 #include "host/host.hpp"
 #include "ipc_policy.hpp"
 #include "stats.hpp"
-#include "sync/spin_ebo_block_mutex.hpp"
 #include "wf_coal_policy.hpp"
 
 namespace rocshmem {