Be more verbose about aggregated memory allocations

The memory profiler aggregates allocations originating from the same
QML/JS constructs into one event. This change makes sure the origins
are really the same calls, not only the same functions and gives some
more details on hom much memory was allocated or deallocated in how
many steps.

Change-Id: I784c521855122f7b3b894417de0afb216766e2d4
Reviewed-by: Kai Koehne <kai.koehne@digia.com>