Debian: Ignore symbol changes on the master branch

Fixes #18404.

.gitlab-ci.yml

@@ -214,6 +214,8 @@ Debian Stable APT Package:
     - export DEB_BUILD_OPTIONS="nocheck parallel=$(( $(getconf _NPROCESSORS_ONLN) + 2 ))"
     - export DH_QUIET=1
     - export MAKEFLAGS=--silent
+    # Ignore changed symbols (on development branch).
+    - export DPKG_GENSYMBOLS_CHECK_LEVEL=0
     - CC=/usr/lib/ccache/gcc CXX=/usr/lib/ccache/g++ dpkg-buildpackage -b --no-sign -jauto -zfast
     - lintian --suppress-tags library-not-linked-against-libc,copyright-excludes-files-in-native-package --display-experimental --display-info --pedantic --profile debian
     - mkdir debian-packages
@@ -296,6 +298,8 @@ Ubuntu APT Package:
     # build-ubuntu puts us in `build`.
     - cd ..
     - ln --symbolic --no-dereference --force packaging/debian
+      # Ignore changed symbols (on development branch).
+    - export DPKG_GENSYMBOLS_CHECK_LEVEL=0
     - CC=/usr/lib/ccache/gcc CXX=/usr/lib/ccache/g++ MAKE=ninja dpkg-buildpackage -us -uc -rfakeroot -jauto -zfast
     - mkdir ubuntu-packages
     - mv ../*.deb ubuntu-packages/

packaging/debian/rules

@@ -7,9 +7,6 @@
 # Uncomment this to turn on verbose mode.
 #export DH_VERBOSE=1
 
-# Catch symbol additions.
-export DPKG_GENSYMBOLS_CHECK_LEVEL=4
-
 distrelease  := $(shell lsb_release -cs)
 ifeq ($(distrelease),n/a)
   distrelease     := sid