RFR: 8266545: 8261169 broke Harfbuzz build with gcc 7 and 8 [v2]

[Thomas Stuefe]

> Harfbuzz upgrade broke Linux x64 build on older gccs. For details see JBS issue.
> 
> I fixed the issue in the harfbuzz sources, but I am not sure of the policy here. Do we modify the harfbuzz sources or leave them untouched? Advice is welcome.
> 
> The patch fixes linux x64 fastdebug and opt build for me.

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

  switch off warning in build instead of fixing it

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3873/files
  - new: https://git.openjdk.java.net/jdk/pull/3873/files/dd0f4d29..bcdc7a54

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3873&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3873&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3873.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3873/head:pull/3873

PR: https://git.openjdk.java.net/jdk/pull/3873