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

[Magnus Ihse Bursie]

On Fri, 18 Mar 2022 01:50:56 GMT, Ichiroh Takiguchi <itakiguchi at openjdk.org> wrote:

> 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

make/autoconf/flags-ldflags.m4 line 80:

> 78: 
> 79:   elif test "x$TOOLCHAIN_TYPE" = xxlc; then
> 80:     # -bexpall should be used instead of -bnoexpall if -qvisibility option is not defined

If you hard-code for the assumption that xlc v16 is being used, then this comment does not make any sense..?

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