[11u] RFR: 8224474: harfbuzz 2.3.1 code fails to compile with gcc 4.4.7

[Severin Gehwolf]

Hi,

Could I please get a review for this JDK 11u only fix? harfbuzz has
been upgraded to 2.3.1 between jdk-11.0.4+2 and jdk-11.0.4+3.
Unfortunately, this breaks the JDK 11u build on CentOS/RHEL 6 with
system GCC 4.4.7 which the upstream OpenJDK 11u builds machinery uses.

The fix is rather trivial: Move GCC pragmas outside functions.

webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8224474/01/webrev/
bug: https://bugs.openjdk.java.net/browse/JDK-8224474

Testing: release/slowdebug builds on Linux x86_64 with gcc 4.4.7.
         fastdebug build on Linux x86_64 with gcc 8.3.1

Thoughts?

Thanks,
Severin