Fix INTERFACE64 not propagating to the fortran codes on ARMV8

[martin-frbg]

fixes #2497

[tylerjereddy]

Nice! cc @mattip

[mattip]

Thanks for the fix. Can we somehow get a tag on this so that git describe --tags, used by our bundler for the names of the tarballs on the anaconda.org arcive get 0.3.9 in the name rather than v0.3.7-484-g4e1c4e67? Also, it may be time to merge develop back into master.

[martin-frbg]

Tags are currently on the 0.3.0 branch only, from where the releases get prepared. master has been dormant for the past two years. There should be a new release in the not too distant future, I just try to keep some balance between delaying bugfixes and making OpenBLAS too much of a moving target.