7145537: minor tweaks to LogEvents
Reviewed-by: kvn, twisti
A few minor fixes and corrections to the LogEvents output. Add the
compile id and osr flag to the nmethod logging. Switch all the times
to the seconds since JVM start and print in standard %.3f format.
Override PrintHeapAtGCExtended when logging the heap. Move
Events::print to the cpp to ease invoking it from the debugger. I
also restored the extern "C" events() function to use when the
debugger is being difficult about invoking C++ methods. I also
expanded the logging of implicit exceptions to record more cases. I
considered removing the generate implicit exception logging since
that's not as rare as the others. Tested with crashing the JVM.