RFR: 8319268: Build failure with GCC8.3.1 after 8313643 [v2]

[null]

> Build failure with GCC8.3.1
> 
> === Output from failing command(s) repeated here ===
> * For target support_native_java.desktop_libfontmanager_hb-ot-layout.o:
> /data/codes/bobjdk/src/java.desktop/share/native/libharfbuzz/hb-ot-layout.cc: In function 'hb_bool_t hb_ot_layout_get_font_extents(hb_font_t*, hb_direction_t, hb_tag_t, hb_tag_t, hb_font_extents_t*)':
> /data/codes/bobjdk/src/java.desktop/share/native/libharfbuzz/hb-ot-layout.cc:2136:26: error: 'max' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>        extents->ascender = max;
>        ~~~~~~~~~~~~~~~~~~~^~~~~
> /data/codes/bobjdk/src/java.desktop/share/native/libharfbuzz/hb-ot-layout.cc:2137:26: error: 'min' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>        extents->descender = min;
>        ~~~~~~~~~~~~~~~~~~~^~~~~
> At global scope:
> cc1plus: error: unrecognized command line option '-Wno-dangling-reference' [-Werror]
> cc1plus: all warnings being treated as errors
> 
> * All command lines available in /data/codes/bobjdk/build/linux-x86_64-server-release/make-support/failure-logs.
> === End of repeated output ===
> 
> No indication of failed target found.
> HELP: Try searching the build log for '] Error'.
> HELP: Run 'make doctor' to diagnose build problems.
> 
> make[1]: *** [main] Error 1
> make: *** [images] Error 2

null has updated the pull request incrementally with one additional commit since the last revision:

  add comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16468/files
  - new: https://git.openjdk.org/jdk/pull/16468/files/f316413a..c4f20e30

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16468&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16468&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16468.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16468/head:pull/16468

PR: https://git.openjdk.org/jdk/pull/16468