RFR (backport of): 8028391 - Make the Min/MaxHeapFreeRatio flags manageable

[Jesper Wilhelmsson]

Hi,

The patch from jdk9/hs-gc to make MinHeapFreeRatio and MaxHeapFreeRatio 
manageable flags and supported in ParallelGC applied cleanly to jdk8u/hs-dev.

hsx/jdk7u60 required some manual labor to patch since the argument parsing code 
had moved around, but the relevant logic was untouched so I didn't have to 
change anything in the new code. For 7 I omitted some of the minor cleanups that 
was done in the original patch.

Webrev for 7: http://cr.openjdk.java.net/~jwilhelm/8028391/webrev.7u60/
Webrev for 8: http://cr.openjdk.java.net/~jwilhelm/8028391/webrev.8u20/

(The 8u20 webrev is identical with the final version for 9.)

So kindly approve this change for backport to jdk8u20 and jdk7u60.

The bugs:
jdk9: https://bugs.openjdk.java.net/browse/JDK-8028391
jdk8: https://bugs.openjdk.java.net/browse/JDK-8033209
jdk7: https://bugs.openjdk.java.net/browse/JDK-8028720

Reviews in this thread:
http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2014-January/009187.html

The jdk9 changeset:
http://hg.openjdk.java.net/jdk9/hs-gc/hotspot/rev/44315152d434

Thanks,
/Jesper