BINARY=64 not set on aarch64

[staticfloat]

I'm not certain if this is an unintentional oversight or something more profound, but our Makefile system does not set BINARY=64 on aarch64. This, in turn, causes OpenBLAS to be built (from source) as an LP64 (e.g. not an ILP64) build, which in turn causes us to build OpenBLAS as LP64 in Yggdrasil, which is not in line with our other 64-bit platforms such as x86_64 and powerpc64le.

I think we probably want to build OpenBLAS as ILP64 and set BINARY=64 on aarch64.

[staticfloat]

Pinging a randomized subset of the linear algebra crew to see if there is any reason ILP64 might be disabled on aarch64.

@ViralBShah @andreasnoack @simonbyrne

[simonbyrne]

Need to contact this guy: #31399

[staticfloat]

I knew there was a reason I pinged you Simon.

[ViralBShah]

Yeah, we should probably go to ILP64 on aarch64. It will also require a bunch of BB stuff to be rebuilt.

[matbesancon]

So this will be blocking JuliaLang/LinearAlgebra.jl#807 if I understand correctly?

[ViralBShah]

#39455 turns on ILP64 BLAS for aarch64, and passes all tests, so this does not block JuliaLang/LinearAlgebra.jl#807 (surprisingly). I do wonder if BINARY=64 should be turned on as well (assuming -m64 can be accepted by gcc/clang on aarch64).

[ViralBShah]

-m64 is not accepted by GCC on arm. So nothing else to be done here.