RFR: 8257913: Add more known library locations to simplify Linux cross-compilation [v2]

[Aleksey Shipilev]

On Fri, 5 Mar 2021 07:06:24 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> I think that value should be accessible from OPENJDK_TARGET_AUTOCONF_NAME.
>
> Yes, original `openjdk-target` would be enough. Unfortunately, `AUTOCONF_NAME` seems to be the quadruplet generated from original `--openjdk-target`. For example, for ARM we supply `--openjdk-target=arm-linux-gnueabihf`, but `OPENJDK_TARGET_AUTOCONF_NAME` is `arm-unknown-linux-gnueabihf`, which is not the same as the subdirectory `arm-linux-gnueabihf`. I don't see how can I get the original `--openjdk-target` provided by user here. Seems to me it is not passed to autoconf?
> 
> I'd be happy to use original `openjdk-target` if I understood how to pass it through... Without it, we have to resort listing gnu* variants for the platforms we build for.

What I can do is parse the ABI from the original string, and then reconstruct the triplet as `$OPENJDK_TARGET_CPU-linux-$OPENJDK_TARGET_ABI`. See the update.

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PR: https://git.openjdk.java.net/jdk/pull/2833