RFR (XS): 8020598: ObjectCountEventSender::send needs INCLUDE_TRACE guards when building OpenJDK with INCLUDE_TRACE=0

[Erik Helin]

Hi all,

this small change ensures that the code compiles when the define
INCLUDE_TRACE is 0.

The problem was that ObjectCountEventSender::send called
Tracing::is_event_enabled in an assert, and Tracing::is_event_enabled is
not defined when INCLUDE_TRACE is 0.

Webrev:
http://cr.openjdk.java.net/~ehelin/8020598/webrev.00/

Testing:
- JPRT
- Building the code with INCLUDE_TRACE set to 0

Bug:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8020598

Thanks,
Erik