Merge bitcoin/bitcoin#21812: ci: Enable D_GLIBCXX_DEBUG for multiprocess task

fa44f51 ci: Clarify that previous_releases task is using DEBUG (MarcoFalke)
fad0f21 ci: Use clang in multiprocess task to avoid OOM (MarcoFalke)
faeabef ci: Enable D_GLIBCXX_DEBUG for multiprocess task (MarcoFalke)

Pull request description:

  Enable `-D_GLIBCXX_DEBUG` via the depends `DEBUG` flag. Also `--enable-debug` to get debug symbols in traces.

ACKs for top commit:
  hebasto:
    ACK fa44f51, I have reviewed the code and it looks OK, I agree it can be merged, and CI is green.

Tree-SHA512: ab2a216bb44ee462f9dd181ec9025962502bd4201a1118ff52b6a193398e7ea3ca465a45a5eb341e308758fc3ef34ea3521f8a1f85ed64478ef3c1f6c1b8b141

Author: fanquake

.cirrus.yml

@@ -112,7 +112,7 @@ task:
     FILE_ENV: "./ci/test/00_setup_env_i686_centos.sh"
 
 task:
-  name: '[previous releases, uses qt5 dev package and some depends packages] [unsigned char] [bionic]'
+  name: '[previous releases, uses qt5 dev package and some depends packages, DEBUG] [unsigned char] [bionic]'
   previous_releases_cache:
     folder: "releases"
   << : *GLOBAL_TASK_TEMPLATE
@@ -161,7 +161,7 @@ task:
     FILE_ENV: "./ci/test/00_setup_env_native_fuzz.sh"
 
 task:
-  name: '[multiprocess] [focal]'
+  name: '[multiprocess, DEBUG] [focal]'
   << : *GLOBAL_TASK_TEMPLATE
   container:
     image: ubuntu:focal

ci/test/00_setup_env_native_multiprocess.sh

@@ -8,9 +8,9 @@ export LC_ALL=C.UTF-8
 
 export CONTAINER_NAME=ci_native_multiprocess
 export DOCKER_NAME_TAG=ubuntu:20.04
-export PACKAGES="cmake python3"
-export DEP_OPTS="MULTIPROCESS=1"
+export PACKAGES="cmake python3 llvm clang"
+export DEP_OPTS="DEBUG=1 MULTIPROCESS=1"
 export GOAL="install"
-export BITCOIN_CONFIG="--enable-external-signer"
+export BITCOIN_CONFIG="--enable-external-signer --enable-debug CC=clang CXX=clang++"  # Use clang to avoid OOM
 export TEST_RUNNER_ENV="BITCOIND=bitcoin-node"
 export RUN_SECURITY_TESTS="true"