RFR: 8250876: Build system preparation to macos on aarch64

[Kim Barrett]

> On Aug 13, 2020, at 6:54 AM, Magnus Ihse Bursie <magnus.ihse.bursie at oracle.com> wrote:
> 
> On 2020-08-13 09:15, Kim Barrett wrote:
>> I'm similarly surprised by this pre-existing bit in CoreLibraries.gmk:
>> 
>> $(eval $(call SetupJdkLibrary, BUILD_LIBJIMAGE, \
>> ...
>>     LIBS_unix := -ljvm -ldl $(LIBCXX), \
>>     LIBS_macosx := -lc++, \
>> 
>> And that suggests a better place for all this (assuming its needed at
>> all) is in lib-std.m4, setting LIBCXX for macosx and using it where
>> needed.
> Yes, that looks weird. Probably some left-over from the initial integration of libjimage. I can build fine locally without it; I'm just verifying that it also works in the CI. Thank you for noticing this!

I just filed https://bugs.openjdk.java.net/browse/JDK-8251533 for that.