Things are often equivalent but different types:
1. u8 arrays in libwally.
2. sha256
3. Secrets derived via sha256
4. txids
Rather than open-coding a BUILD_ASSERT & memcpy, create a macro to do it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).
af90fdc0bb