RFR Backport: 8166663: Simplify oops_on_card_seq_iterate_careful

[Yangfei (Felix)]

Hi,

As mentioned in [1], JDK-8160369 have not been backported to JDK8u. This is necessary for RMO architectures like aarch64.

JDK-8166607 is a subtask of JDK-8160369.  But JDK-8166607 depends on JDK-8166663, so backport JDK-8166663 first.

Original bug: https://bugs.openjdk.java.net/browse/JDK-8166663 
Original patch: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/e6e9117c4fec 
Original review thread: https://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2016-September/019045.html 

The original patch for JDK-8166663 does not apply cleanly to jdk8u-dev due to path and code refactoring work in jdk9+.
Also we need to wrap the error message using err_msg since we don't have the enhanced version of assert in jdk9+.

Webrev for 8u:
    http://cr.openjdk.java.net/~fyang/8166663-8u/webrev.00/

Performed full jtreg test with release build both on aarch64-linux and x86_64-linux platforms.
Also ran jcstress on both platforms.  OK to backport?

Thanks,
Felix

[1] https://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2020-July/030313.html