Fix: support 64-bit events discarded counter types

Fix: support 64-bit events discarded counter types

Previously, counters coming for 64-bit architectures would be treated in
the same way as 32-bit counters, and would therefore miss 32-bit
overflows (only happens if 2^32 events or more are lost within in a
packet).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>