P4
If os::loadavg is unsupported (as is the case on Windows) recent_load will be used with a indeterminate uninitialised value, resulting in a strange log-line.
Example output (when os::loadavg returns -1):
```
./images/jdk/bin/java -Xlog:gc -Xlog:gc+periodic=debug -XX:G1PeriodicGCInterval=1 -XX:G1PeriodicGCSystemLoadThreshold=1 --version
[0.015s][info][gc] Using G1
[0.052s][debug][gc,periodic] Checking for periodic GC.
[0.052s][debug][gc,periodic] Load -5314010372517807647283750286542177604307566955124202298657110301286024565751467488997011497523400915218988848162908025095251475452883610273262870620813970880702873922007837303063754086453326881912422810930200791418157490736660992630758605035109999689038468218762046137453549407645927178560594162686623744.00 is higher than threshold 1.00. Skipping.
```
Example output (when os::loadavg returns -1):
```
./images/jdk/bin/java -Xlog:gc -Xlog:gc+periodic=debug -XX:G1PeriodicGCInterval=1 -XX:G1PeriodicGCSystemLoadThreshold=1 --version
[0.015s][info][gc] Using G1
[0.052s][debug][gc,periodic] Checking for periodic GC.
[0.052s][debug][gc,periodic] Load -5314010372517807647283750286542177604307566955124202298657110301286024565751467488997011497523400915218988848162908025095251475452883610273262870620813970880702873922007837303063754086453326881912422810930200791418157490736660992630758605035109999689038468218762046137453549407645927178560594162686623744.00 is higher than threshold 1.00. Skipping.
```