gitlab-ci: add linux32 job testing against i386

Add another job to GitLab CI that tests against the i386 architecture.
This job is equivalent to the same job in GitHub Workflows.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.gitlab-ci.yml

@@ -66,6 +66,8 @@ test:linux:
         image: fedora:latest
       - jobname: linux-musl
         image: alpine:latest
+      - jobname: linux32
+        image: i386/ubuntu:20.04
       - jobname: linux-meson
         image: ubuntu:latest
         CC: gcc

ci/lib.sh

@@ -269,7 +269,7 @@ then
 		CI_OS_NAME=osx
 		JOBS=$(nproc)
 		;;
-	*,alpine:*|*,fedora:*|*,ubuntu:*)
+	*,alpine:*|*,fedora:*|*,ubuntu:*|*,i386/ubuntu:*)
 		CI_OS_NAME=linux
 		JOBS=$(nproc)
 		;;