RFR: 8204541: Correctly support AIX xlC 16.1 symbol visibility flags

[Ichiroh Takiguchi]

This change is just for AIX platform with IBM XL C/C++ 16.1.
By this change, lib's entry points are reduced by compilation and linkage option changes.

Without changes:

$ dump -X32_64 -Tv lib/libawt.so | grep EXP | wc
914

With changes

$ dump -X32_64 -Tv lib/libawt.so | grep EXP | wc
142

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

Commit messages:
 - 8204541: Correctly support AIX xlC 16.1 symbol visibility flags

Changes: https://git.openjdk.java.net/jdk/pull/7862/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7862&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8204541
  Stats: 13 lines in 3 files changed: 7 ins; 2 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7862.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7862/head:pull/7862

PR: https://git.openjdk.java.net/jdk/pull/7862