Multiprocess unit test various fixes (#367)

* Re-enabling mp unit tests

* Fixing shared memory leak and other bugs related to shared mem for MP unit tests

* Revert 43bfbfc97bf9edbae1f386d461439091618ff8ed

* Further tightening up unlinks

* Moving test check macros to separate header file

* Tightening up shared memory unlinking for clique kernels, add munmap for host barrier for MP unit tests

* Updating new MP unit test

* Fixing mqueue bug

* Fixing memory leak in MP unit tests

[ROCm/rccl commit: 0b2bfdd6d8]

projects/rccl/test/test_GroupCallsMultiProcess.cpp

@@ -60,6 +60,7 @@ namespace CorrectnessTests
 
         for (int i = 0; i < datasets.size(); i++)
         {
+            datasets[i]->ReleaseRootProcess();
             munmap(datasets[i], sizeof(Dataset));
         }
     }