hg: jdk/sandbox: 8240615: is_power_of_2() has Undefined Behaviour and is inconsistent

[chris.hegarty at oracle.com]

Changeset: e50512f91026
Author:    aph
Date:      2020-03-10 10:49 -0400
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/e50512f91026

8240615: is_power_of_2() has Undefined Behaviour and is inconsistent
Reviewed-by: jrose, redestad

! src/hotspot/cpu/aarch64/aarch64.ad
! src/hotspot/cpu/x86/x86_64.ad
! src/hotspot/share/utilities/powerOfTwo.hpp
! test/hotspot/gtest/utilities/test_powerOfTwo.cpp