[8u40] RFR 8062870: src/share/vm/services/mallocTracker.hpp:64 assert(_count > 0) failed: Negative ,counter

[Coleen Phillimore]

Please approve the backport of the bug fix for this bug.  The fix has 
been tested all week with no problems.  The patch didn't import because 
MallocTrackingVerify.java didn't have an @ignore tag, which was removed 
by the jdk9 fix.  Everything else applied cleanly.

Summary: Signed bitfield size y can only have (1 << y)-1 values.
Reviewed-by: shade, dholmes, jrose, ctornqvi, gtriantafill

open webrev at http://cr.openjdk.java.net/~coleenp/8062870_8u40/
bug link https://bugs.openjdk.java.net/browse/JDK-8062870

Thanks!
Coleen