RFR: 8312592: New parentheses warnings after HarfBuzz 7.2.0 update

[Aleksey Shipilev]

At least GCC 6 fail the build with warnings-as-errors here:


../src/java.desktop/share/native/libharfbuzz/hb-subset-plan.cc: In function 'void _collect_layout_variation_indices(hb_subset_plan_t*)':
../src/java.desktop/share/native/libharfbuzz/hb-subset-plan.cc:389:83: error: suggest parentheses around assignment used as truth value [-Werror=parentheses]
     if (unlikely (!plan->check_success (font = _get_hb_font_with_variations (plan)))) {
                                                                                   ^
../src/java.desktop/share/native/libharfbuzz/hb.hh:259:46: note: in definition of macro 'unlikely'
 #define unlikely(expr) (__builtin_expect (!!(expr), 0))
                                              ^~~~


This is caused by HarfBuzz update to 7.2.0, [JDK-8307301](https://bugs.openjdk.org/browse/JDK-8307301)

Instead of fixing the HarfBuzz sources in-tree, it is cleaner to disable the warning. Lots of follow-ups after this HarfBuzz update did the same.

Additional testing:
 - [x] Linux x86_64 fastdebug build on affected systems

-------------

Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/14996/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14996&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312592
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14996.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14996/head:pull/14996

PR: https://git.openjdk.org/jdk/pull/14996