Request for reviews (S): 6681577: PIT: some VM tests fails with -XX:+AggressiveOpts in 6u5p b01

[Vladimir Kozlov]

http://webrev.invokedynamic.info/kvn/6681577/index.html

Fixed 6681577: PIT: some VM tests fails with -XX:+AggressiveOpts in 6u5p b01

Problem:
C2 spends > 60% in escape analysis code during test nsk/regression/b4675027.
Most of the time it spends in ConnectionGraph::remove_deferred().

Solution:
Optimize the method ConnectionGraph::remove_derefered().
EA performance improved by x5.

Reviewed by:
Fix verified (y/n): y, failed test cases.

Other testing:
JPRT