Add cstring header explictly as it is removed from HIP (#132)

[ROCm/rccl-tests commit: 0039629ac5]

projects/rccl-tests/src/common.h

@@ -11,6 +11,7 @@
 #include "rccl/rccl.h"
 #include <stdio.h>
 #include <cstdint>
+#include <cstring>
 #include <algorithm>
 #ifdef MPI_SUPPORT
 #include "mpi.h"