testing/multimc: add missing dependency on libxcursor

Without libxcursor game window contains several cursors
8 jobs for !23750 with multimc in 1 minute and 23 seconds (queued for 4 seconds)
latest detached
Status Job ID Name Coverage
  Lint
passed #450463
docker-alpine x86_64
lint

00:00:19

 
  Build
passed #450468
docker-alpine ci-build aarch64
build-aarch64

00:00:29

passed #450470
docker-alpine ci-build armhf
build-armhf

00:00:29

passed #450469
docker-alpine ci-build armv7
build-armv7

00:00:29

passed #450467
docker-alpine ci-build ppc64le
build-ppc64le

00:01:03

passed #450466
docker-alpine ci-build s390x
build-s390x

00:00:36

passed #450465
docker-alpine ci-build x86
build-x86

00:00:16

passed #450464
docker-alpine ci-build x86_64
build-x86_64

00:00:17