hg: jdk/jdk: 8235551: BitMap::count_one_bits should use population_count

[claes.redestad at oracle.com]

Changeset: 0d33d0db0c96
Author:    redestad
Date:      2019-12-11 16:24 +0100
URL:       https://hg.openjdk.java.net/jdk/jdk/rev/0d33d0db0c96

8235551: BitMap::count_one_bits should use population_count
Reviewed-by: kbarrett, neliasso
Contributed-by: kim.barrett at oracle.com, claes.redestad at oracle.com

! src/hotspot/share/opto/regmask.cpp
! src/hotspot/share/utilities/bitMap.cpp
! src/hotspot/share/utilities/bitMap.hpp
! src/hotspot/share/utilities/population_count.hpp
! test/hotspot/gtest/utilities/test_population_count.cpp