only time inference if any work is actually done

[KristofferC]

Otherwise, this can give a huge number of instant events, for example when profiling the creation of corecompiler.ji

[topolarity]

I think when I tested I didn't see any major overhead from all of these events during sysimage generation, but it's probably still nice to keep the "useless" events down in volume

[KristofferC]

When enabling stack probing I think they caused a significant overhead. Timing corecompiler.ji there where tens of millions of these generated.