hg: jdk/jdk: 8217869: Add count_leading_zeros utility

[claes.redestad at oracle.com]

Changeset: bc20d0376402
Author:    redestad
Date:      2019-01-28 23:00 +0100
URL:       http://hg.openjdk.java.net/jdk/jdk/rev/bc20d0376402

8217869: Add count_leading_zeros utility
Reviewed-by: neliasso, thartmann

! src/hotspot/share/opto/regmask.cpp
! src/hotspot/share/opto/regmask.hpp
+ src/hotspot/share/utilities/count_leading_zeros.hpp
+ test/hotspot/gtest/utilities/test_count_leading_zeros.cpp
! test/hotspot/gtest/utilities/test_count_trailing_zeros.cpp