Redesign the feature set

[IvanUkhov]

Hello,

This question is inspired by the conversation in blas-lapack-rs/lapack-src#11.

Would you maybe be willing to change the feature set from

• mkl-static-lp64-iomp,
• mkl-static-lp64-seq,
• mkl-static-ilp64-iomp,
• mkl-static-ilp64-seq,
• mkl-dynamic-lp64-iomp,
• mkl-dynamic-lp64-seq,
• mkl-dynamic-ilp64-iomp, and
• mkl-dynamic-ilp64-seq

to

• static and dynamic,
• lp64 and ilp64, and
• iomp and seq

with errors raised from the build script whenever the active combination does not make sense, such as when activating lp64 together with ilp64? The primary motivation is to allow other libraries to make some choices but not all. In the case of the issue linked above, we would want to preselect lp64 but leave the rest up to the user without having to invent our own features.