Substitute pow2bin allocator with a dlmalloc based allocator (#71)

* Add dlmalloc_strat allocator strategy
 - Use mspace variant to ease encapsulation
 - Make pow2bins and dlmalloc cmake selectable
* Add unit tester for dlmalloc, rework single_heap, pow2bins unit testers
accordingly
 - add dlmalloc get_used/get_avail, and have all strats allocators also have a get_used
 - Rework memallocator unit tests: bin size is per strat, alignment is verified in singleheap
* bugfix: dlmalloc exposed that the pingpong test would write past end of
allocation with -w 32
* iostream leakage/mixed usage of cerr and fprintf(stderr

---------

Signed-off-by: Aurelien Bouteiller <aurelien.bouteiller@amd.com>

cmake/rocshmem_config.h.in

@@ -33,6 +33,8 @@
 #cmakedefine USE_MANAGED_HEAP
 #cmakedefine USE_HOST_HEAP
 #cmakedefine USE_HIP_HOST_HEAP
+#cmakedefine USE_ALLOC_DLMALLOC
+#cmakedefine USE_ALLOC_POW2BINS
 #cmakedefine USE_FUNC_CALL
 #cmakedefine USE_SINGLE_NODE
 #cmakedefine USE_HOST_SIDE_HDP_FLUSH