Request for reviews (update)(S): 6863420: os::javaTimeNanos() go backward on Solaris x86]

[Vladimir Kozlov]

I updated the fix to use Atomic::load() always as David H. suggested.

http://cr.openjdk.java.net/~kvn/6863420/webrev.01

Fixed 6863420: os::javaTimeNanos() go backward on Solaris x86

Problem:
The problem is non atomic load from max_hrtime in getTimeNanos()
on platforms where long is kept in 2 32-bit register.
The loaded value could be invalid (> current time) since registers
are loaded separately and store could happened in between.
It could be returned as result if it is greater then current time.
And if the next call getTimeNanos() returns the correct time
it will be less then previous result.

Solution:
Use new atomic long load method Atomic::load() which uses
FPU to move long value atomically on 32-bit x86 or
simply returns *src in other cases.

Added the regression test which shows the problem.

Reviewed by:

Fix verified (y/n): y, regression test

Other testing:
JPRT, ScaleHarness(6784100)