add ECMULT_GEN_PREC_BITS to basic_config.h

[voisine]

set ECMULT_GEN_PREC_BITS to the "auto" value of 4 in basic_config.h, so libsecp can be used without autoconf

[real-or-random]

Thanks for the PR, this is indeed a bug! However, fixing it requires some more cleanup (see CI failures).

I'm currently playing around with some options. I should have something ready by tomorrow.

[real-or-random]

By the way, how do you use this library without autoconf? Do you simply #include it or do you build it and then link it? In either case I'd we interested in the exact method, e.g.: How do you define your config? Do you include basic-config.h? What's the command line?

This could help us towards #622.

[voisine]

Thank you. Currently I just #include basic_config.h and then the appropriate libsecp implementations, but I eventually plan to add the source files to an external build system other than “make”

[voisine]

Specifically I want to be able to build using Xcode on a clean OS X install without installing additional build tools like autoconf.

[jonasnick]

Superseded by #918 (merged)

[voisine]

Excellent. My commit even managed to survive into the final merge. Thank you.