RFR(xxs): 8241419: Remove unused InterfaceSupport::_number_of_calls

[Jie He]

Hi

May I please have reviews for this cleanup.

The variable InterfaceSupport::_number_of_calls is actually not used.

The place to set the variable is in macro TRACE_CALL, as below:

ifdef ASSERT
#define TRACE_CALL(result_type, header) \
InterfaceSupport::_number_of_calls++; \
if (CountRuntimeCalls) { \
     static RuntimeHistogramElement* e = new RuntimeHistogramElement(#header); \
     if (e != NULL) e->increment_count();                                     \
}
#define TRACE_CALL(result_type, header) \
/* do nothing */
#endif // ASSERT

But can't find the use place of this variable, so assume it's a useless variable.

After check the history, found a patch in jdk9 https://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/fb4a19e4f7dc
which said, "Removed TraceRuntimeCalls, TraceJNICalls, and TraceJVMCalls options because their output is excessive, not useful, and covered in a more useful way by other options."
so I think it's the leftover of the patch, should be removed.

Issue: https://bugs.openjdk.java.net/browse/JDK-8241419
webrev: http://cr.openjdk.java.net/~yzhang/8241419/webrev.00/

Thanks
Jie He