Precompiled libraries for Win32.

GNU Nettle 3.4: https://www.lysator.liu.se/~nisse/nettle/
- License: LGPLv3 or LGPLv2.1
- ASM optimizations are enabled in "fat binary" mode.
- i386 build:
  - Compiled with i686-w64-mingw32-gcc 7.3.0.
  - i686-optimized.
- amd64 build:
  - Compiled with x86_64-w64-mingw32-gcc 7.3.0.
