Add symbolprefix=scipy

[mattip]

It turns out we need to add a symbol prefix in order to use the wheels, otherwise there are clashes with other builds of OpenBLAS and/or other BLAS implementations. This adds a SYMBOLPREFIX=scipy to these builds. Also

• update the OpenBLAS hash to latest HEAD
• update the OpenBLAS and multibuild subrepos (not necessarily required)

[mattip]

This is ready if anyone wants to review. I don't think we need to change the wheel names for the changed function names. This is a new version 0.3.24.95 and the changed prefix requires no external code changes.

[rgommers]

I'll note that if this is needed again in the future or changes, there's a better way than hardcoding it. The path can be obtained from xcrun --sdk macosx --show-sdk-path. I just managed to get rid of this hardcoding in numpy CI.

[mattip]

I added a comment in the commit to add the BLAS_SYMBOL_PREFIX definition to the pkgconfig file

[mattip]

Currently if you use the ILP64 builds, you have to add -Duse-ilp64=true which ends up defining OPENBLAS_ILP64_NAMING_SCHEME. We have cflags in the pkgconfig file, so I added the macro there. Once use of these newer wheels is normalized we can remove the meson flag.

[rgommers]

We can't in general, because there are libraries that have both LP64 and ILP64 symbols. True right now for at least MKL and Accelerate, and may also be true for OpenBLAS sometime next year (after reference BLAS/LAPACK adopts it). It has to be a user opt-in. It may be okay for the opt-in to be automatic for scipy-openblas, less sure of that.

[mattip]

It may be okay for the opt-in to be automatic for scipy-openblas, less sure of that.

It worked locally, with the latest commit I can do

PKG_CONFIG_PATH=$PWD/.openblas
pip install scipy-openblas64
spin build --with-scipy-openblas=64  # without -- -Duse-ilp64=true