Add rocr namespace to core header and impl files

Change-Id: I1e1b33f9bba1078d049bc19797889988c3e43360

runtime/hsa-runtime/core/util/small_heap.cpp

@@ -42,6 +42,8 @@
 
 #include "small_heap.h"
 
+namespace rocr {
+
 // Inserts node into freelist after place.
 // Assumes node will not be an end of the list (list has guard nodes).
 void SmallHeap::insertafter(SmallHeap::iterator_t place, SmallHeap::iterator_t node) {
@@ -179,3 +181,5 @@ void* SmallHeap::alloc_high(size_t bytes) {
   // Can't service the request due to fragmentation
   return nullptr;
 }
+
+}  // namespace rocr