Update os_heap.h
Update os_heap.h

Fix for #37 : Opensplice 6.7 triggers internal compiler error with gcc 7.1
osrf/opensplice,osrf/opensplice,osrf/opensplice,osrf/opensplice,osrf/opensplice,osrf/opensplice,osrf/opensplice,osrf/opensplice,osrf/opensplice