RFR (XS): 8209698: Remove "Pinned" from HeapRegionTraceType

[Thomas Schatzl]

Hi all,

  can I have reviews to remove the "Pinned" category from
HeapRegionTraceType since this is an invalid and anyway unused region
type.

This should not pose a problem with JFR as, from what I understand,
every jfr trace contains the available values.

CR:
https://bugs.openjdk.java.net/browse/JDK-8209698
Webrev:
http://cr.openjdk.java.net/~tschatzl/8209698/webrev/
Testing:
hs-tier1-5,jdk-tier1-3

Thanks,
  Thomas