[8u] [RFR] 8140482: Various minor code improvements (runtime)

[Andrew Hughes]

Bug: https://bugs.openjdk.java.net/browse/JDK-8140482
Original changeset:
https://hg.openjdk.java.net/jdk-updates/jdk9u/hotspot/rev/cd86b5699825
Webrev: https://cr.openjdk.java.net/~andrew/openjdk8/8140482/webrev.01/

The patch largely applies as is, with some adjustment for context and
the dropping of the changes to src/cpu/x86/vm/stubRoutines_x86.cpp,
src/share/vm/runtime/task.cpp and src/os/windows/vm/attachListener_windows.cpp
which don't exist in 8u. A clean backport of 7127191 is included, which
allows the changes to agent/src/os/linux/libproc_impl.c to apply as-is.

Applying the change to 8u improves the code quality there and aids
in backporting other changes, such as 8210836 [0].

Ok for 8u?

[0] https://mail.openjdk.java.net/pipermail/serviceability-dev/2018-November/025991.html

Thanks,
-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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