Merge #18677: Multiprocess build support

e2bab2aa162ae38b2bf8195b577c982402fbee9d multiprocess: add multiprocess travis configuration (Russell Yanofsky)
603fd6a2e708c04ef6c9880f89d0a4cbaa6fc7c5 depends: add MULTIPROCESS depends option (Russell Yanofsky)
5d1377b52bfcd4edf8553aaf332bfeb92fc554cc build: multiprocess autotools changes (Russell Yanofsky)

Pull request description:

  This PR is part of the [process separation project](https://github.com/bitcoin/bitcoin/projects/10).

  ---

  This PR consists of build changes only. It adds an `--enable-multiprocess` autoconf option (off by default and marked experimental), that builds new `bitcoin-node` and `bitcoin-gui` binaries. These currently function the same as existing `bitcoind` and `bitcoin-qt` binaries, but are extended in #10102 with IPC features to execute node, wallet, and gui functions in separate processes.

  In addition to adding the `--enable-multiprocess` config flag, it also adds a depends package and autoconf rules to build with the [libmultiprocess](https://github.com/chaincodelabs/libmultiprocess) library, and it adds new travis configuration to exercise the build code and run functional tests with the new binaries.

  The changes in this PR were originally part of #10102 but were moved into #16367 to be able to develop and review the multiprocess build changes independently of the code changes. #16367 was briefly merged and then reverted in #18588. Only change since #16367 has been dropping the `native_boost.mk` depends package which was pointed out to be no longer necessary in https://github.com/bitcoin/bitcoin/pull/16367#issuecomment-596484337 and https://github.com/bitcoin/bitcoin/pull/18588#pullrequestreview-391765649

ACKs for top commit:
  practicalswift:
    ACK e2bab2aa162ae38b2bf8195b577c982402fbee9d
  Sjors:
    tACK e2bab2aa162ae38b2bf8195b577c982402fbee9d on macOS 10.15.4
  hebasto:
    ACK e2bab2aa162ae38b2bf8195b577c982402fbee9d, tested on Linux Mint 19.3 (x86_64):

Tree-SHA512: b5a76eab5abf63d9d8b6d628cbdff4cc1888eef15cafa0a5d56369e2f9d02595fed623f4b74b2cf2830c42c05a774f0943e700f9c768a82d9d348cad199e135c

3 files changed, 16 insertions, 1 deletions

diff --git a/ci/test/00_setup_env.sh b/ci/test/00_setup_env.sh
index 2c08fdbcd8..deb4643731 100755
--- a/ci/test/00_setup_env.sh
+++ b/ci/test/00_setup_env.sh
@@ -34,6 +34,7 @@ export USE_BUSY_BOX=${USE_BUSY_BOX:-false}
 export RUN_UNIT_TESTS=${RUN_UNIT_TESTS:-true}
 export RUN_FUNCTIONAL_TESTS=${RUN_FUNCTIONAL_TESTS:-true}
 export TEST_PREVIOUS_RELEASES=${TEST_PREVIOUS_RELEASES:-false}
+export TEST_RUNNER_ENV=${TEST_RUNNER_ENV:-}
 export RUN_FUZZ_TESTS=${RUN_FUZZ_TESTS:-false}
 export CONTAINER_NAME=${CONTAINER_NAME:-ci_unnamed}
 export DOCKER_NAME_TAG=${DOCKER_NAME_TAG:-ubuntu:18.04}
diff --git a/ci/test/00_setup_env_native_multiprocess.sh b/ci/test/00_setup_env_native_multiprocess.sh
new file mode 100644
index 0000000000..0fc989085c
--- /dev/null
+++ b/ci/test/00_setup_env_native_multiprocess.sh
@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) 2020 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+export LC_ALL=C.UTF-8
+
+export CONTAINER_NAME=ci_native_multiprocess
+export PACKAGES="cmake python3"
+export DEP_OPTS="MULTIPROCESS=1"
+export GOAL="install"
+export BITCOIN_CONFIG=""
+export TEST_RUNNER_ENV="BITCOIND=bitcoin-node"
diff --git a/ci/test/06_script_b.sh b/ci/test/06_script_b.sh
index ed720bcd00..51d84ee39d 100755
--- a/ci/test/06_script_b.sh
+++ b/ci/test/06_script_b.sh
@@ -37,7 +37,7 @@ fi
 
 if [ "$RUN_FUNCTIONAL_TESTS" = "true" ]; then
   BEGIN_FOLD functional-tests
-  DOCKER_EXEC LD_LIBRARY_PATH=$DEPENDS_DIR/$HOST/lib test/functional/test_runner.py --ci $MAKEJOBS --tmpdirprefix "${BASE_SCRATCH_DIR}/test_runner/" --ansi --combinedlogslen=4000 ${TEST_RUNNER_EXTRA} --quiet --failfast
+  DOCKER_EXEC LD_LIBRARY_PATH=$DEPENDS_DIR/$HOST/lib ${TEST_RUNNER_ENV} test/functional/test_runner.py --ci $MAKEJOBS --tmpdirprefix "${BASE_SCRATCH_DIR}/test_runner/" --ansi --combinedlogslen=4000 ${TEST_RUNNER_EXTRA} --quiet --failfast
   END_FOLD
 fi