[openssl-users] BN_MUL_MONT for ARM64 v8

[Salz, Rich]

> Have you considered using GMP as a big integer backed for openssl?  It has support for several arm variants using handwritten assembly code and the developers go to great lengths to find optimize runtime on all supported platforms.

It might be interesting if we could figure out how to handle it as a dynamic library.  License issues prevent anything else.