libntruprime: Install

Prerequisites:

- `python3` (for: build, test)
- recommended `python3-capstone` (for: build)
- `gcc` and/or `clang` (for: build)
- `valgrind` (for: build, test)
- `libcpucycles` (for: build, bench)
- `librandombytes` (for: build, test, bench, run)

Make sure to test the compiled library. The tests check for subtle security problems that can be created by compilers. A compiled version of libntruprime is not supported unless it passes the full test suite.

### For sysadmins

To install in `/usr/local/{include,lib,bin,man}`:

    ./configure && make -j8 install

### For developers with an unprivileged account

Typically you'll already have

    export LD_LIBRARY_PATH="$HOME/lib"
    export LIBRARY_PATH="$HOME/lib"
    export CPATH="$HOME/include"
    export MANPATH="$HOME/man"
    export PATH="$HOME/bin:$PATH"

in `$HOME/.profile`. To install in `$HOME/{include,lib,bin,man}`:

    ./configure --prefix=$HOME && make -j8 install

### For distributors creating a package

Run

    ./configure --prefix=/usr && make -j8

and then follow your usual packaging procedures for the `build/0/package` files:

    build/0/package/include/ntruprime.h
    build/0/package/lib/libntruprime*
    build/0/package/bin/*ntrup*
    build/0/package/man/man3/*.3
    build/0/package/man/man1/*.1

### More options, part 1: architectures

You can run

    ./configure --host=amd64

to override `./configure`'s guess of the architecture that it should compile for.

Inside the `build` directory, `0` is symlinked to `amd64` for `--host=amd64`. Running `make clean` removes `build/amd64`. Re-running `./configure` automatically starts with `make clean`.

A subsequent `./configure --host=arm64` will create `build/arm64` and symlink `0 -> arm64`, without touching an existing `build/amd64`. However, cross-compilers aren't yet selected automatically.

### More options, part 2

One further `./configure` option is supported for developers: `--no-trim`.

All `./configure` options not listed above are experimental and not supported. Use them at your own risk.

Version: This is version 2024.10.19 of the "Install" web page.