RFR(XS): 8195094: Fix type-O in "8159422: Very high Concurrent Mark mark stack contention"

[Lindenmaier, Goetz]

Hi,

Could I please get a review for this tiny fix? I please need a sponsor, too.
http://cr.openjdk.java.net/~goetz/wr18/8195094-typeO/webrev.01/

The string is interpreted as a bool and the wrong implementation of 
the function is called.
This should go to 10, please.

Best regards,
  Goetz.