community/mlt: fix deadlock due to recursive mutex

See: alpine/aports#11838 (comment 114554)

Fixes #11838
7 jobs for !12613 with mlt-fix-recursive-mutex in 2 minutes and 43 seconds (queued for 2 seconds)
detached
Status Job ID Name Coverage
  Lint
failed #210290
x86_64 docker-alpine allowed to fail
lint

00:00:21

 
  Build
passed #210295
aarch64 ci-build docker-alpine
build-aarch64

00:01:53

passed #210296
armv7 ci-build docker-alpine
build-armv7

00:01:55

passed #210294
ppc64le ci-build docker-alpine
build-ppc64le

00:02:19

passed #210293
s390x ci-build docker-alpine
build-s390x

00:01:06

passed #210292
x86 ci-build docker-alpine
build-x86

00:01:19

passed #210291
x86_64 ci-build docker-alpine
build-x86_64

00:01:11

 
Name Stage Failure
failed
lint Lint
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