coding: simplify ordering of SET OF elements

That moves to using qsort instead of implementing
sorting internally.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>
8 jobs for tmp-simplify-setof-sorting in 39 minutes and 49 seconds (queued for 45 seconds)
Status Job ID Name Coverage
  Test
passed #55985150
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MinGW32

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passed #55985147
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asan

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clang

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passed #55985152
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gnutls

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passed #55985154
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static-analyzers

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ubsan

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x86

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passed #55985141
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x86-64

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