When ENABLE_IPC option is on, build with libmultiprocess subtree and
`add_subdirectory(src/ipc/libmultiprocess)` instead of external package
and `find_package(Libmultiprocess)` by default.

Behavior can be toggled with `WITH_LIBMULTIPROCESS` option. Using a subtree
should be more convenient for most bitcoin developers, but using an external
package is more convenient for developing in the libmultiprocess repository.

The `WITH_LIBMULTIPROCESS` option is also used to avoid needing to changing the
depends build here. But in later commits, the depends build is switched to use
the add_subdirectory build as well.

Co-authored-by: Cory Fields <[email protected]>

This change is technically not needed to add libmultiprocess as a subtree, but
it avoids a CI failure in followup PR bitcoin#30975 which enables multiprocess build
option in more CI jobs. In that PR, several jobs fail due to the mptest
executable not being built by default, as reported
bitcoin#30975 (comment)

This change is technically not needed to add libmultiprocess as a subtree, but
it avoids a CI failure in followup PR bitcoin#30975 which enables multiprocess build
option in more CI jobs. In that PR, the "macOS 14 native no depends job" fails
due to warnings in boost headers treated as errors, reported in
bitcoin#30975 (comment) and
chaincodelabs/libmultiprocess#138

This change is technically not needed to add libmultiprocess as a subtree, but
it avoids a CI failure in followup PR bitcoin#30975 which enables multiprocess build
option in more CI jobs. In that PR, clang-tidy job fails due to missing
generated example files as reported
bitcoin#30975 (comment)

Different fixes were suggested
bitcoin#30975 (comment) and
bitcoin#30975 (comment)

Co-authored-by: Hennadii Stepanov <[email protected]>

Co-authored-by: Cory Fields <[email protected]>

Without this change linter produces errors about:

- Use of std::filesystem the libmultiprocess example program.
- Use of locale-dependent functions in example program, in the build time code
  generator, and in the runtime library for debug logging.
- Include guards not beginning with BITCOIN_

Move parts of the int_get_build_id into a new int_get_build_properties
function. There is no change in behavior. This just organizes assignments
better so some build properties can be used to help compute build ids in the
next commit.

With newly introduced libmultiprocess subtree, there's no need for depends
system to download and track changes to the upstream repository.

Note that adding the libmultiprocess subtree does not allow dropping
libmultiprocess packages from the depends build, because libmultiprocess
includes a code generation tool called mpgen, and in cross-compiled builds,
bitcoin core's cmake build system doesn't have access to a native toolchain and
can't build mpgen itself, so the depends system (or the native environment if
not using depends) needs to supply it.

Co-authored-by: Hennadii Stepanov <[email protected]>

Except:
1. i686, DEBUG (changed to "no multiprocess")
2. Windows due to lack of support

Install capnp where needed.

The bitcoin-node binary is built on all platforms which have
multiprocess enabled, but for functional tests it's only used in
the macOS native (no depends) and CentOS native (depends) jobs.

Except for Windows and OpenBSD.

Allows InitError and InitWarning to be used by other executables beside
bitcoind and bitcoin-node.

See src/bitcoin-mine.cpp for usage information.

Co-authored-by: Sjors Provoost <[email protected]>

For now also build bitcoin-node.

The Template Provider binary:
* won't have a wallet
* probably won't have a gui
* doesn't use the functional test framework

Disable some CI stuff to speed it up.

This is not a complete list, because:
1. That would be too hard to rebase
2. Some things might be added later, e.g. tracepoints