Enable 64-bit array indexing support

Packages describing “index64” as local USE flag

Package“index64” Flag Description
sci-libs/blas-lapack-aux-wrapperCreate ILP64 wrappers as well
sci-libs/blisBuild an ILP64 libblis64 in addition to LP64 libblis
sci-libs/flexiblasBuild a separate ILP64 library in addition to LP64
sci-libs/lapackBuild a separate ILP64 library in addition to LP64
sci-libs/openblasCompile a separate INTERFACE64 OpenBLAS
virtual/blasProvide an ILP64 library in addition to LP64
virtual/cblasProvide an ILP64 library in addition to LP64
virtual/lapackProvide an ILP64 library in addition to LP64
virtual/lapackeProvide an ILP64 library in addition to LP64

All packages providing a “index64” USE flag (10)