qtdemux: Allow a sample for multple output streams

A sample of meta item (such as an image) can be also other stream's sample.
15 jobs for heif-support in 53 minutes and 40 seconds (queued for 3 seconds)
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gst indent

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manifest

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build fedora x86_64

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build nodebug fedora x86_64

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check fedora

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integration testsuites fedora

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  Full Builds
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build cerbero android universal

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build cerbero cross win32

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build cerbero cross win64

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build cerbero fedora x86_64

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  Full Tests
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valgrind bad

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valgrind ges

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valgrind good

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  Apps
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android universal examples

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  Deploy
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documentation

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