[jdk11u-dev] RFR: 8283323: libharfbuzz optimization level results in extreme build times

[Tyler Steele]

This PR backports changes to improve build performance with xlc.

It appears that the file was at `make/modules/java.desktop/lib/Awt2dLibraries.gmk` when  this commit was made, but that file has since been moved to `make/lib/Awt2dLibraries.gmk`. This made the change show up as a conflict when I applied this backport using the Skara tools. I resolved the 'conflict' by copying the changes to the new path and marking the previous path as removed.

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

Commit messages:
 - 8283323: libharfbuzz optimization level results in extreme build times

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/1077/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=1077&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283323
  Stats: 8 lines in 1 file changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/1077.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/1077/head:pull/1077

PR: https://git.openjdk.java.net/jdk11u-dev/pull/1077