Add missing ffmpeg-4-fit/libavcodec/crystalhd.c from ffmpeg 4.2, #2271

[gaod]

ffmpeg-4-fit/libavcodec/crystalhd.c was missing that cause compiling failed in Ubuntu 18.04/20.4.

[codecov-commenter]

Codecov Report

Merging #2444 (f20b07c) into 4.0release (aa12251) will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           4.0release    #2444   +/-   ##
===========================================
  Coverage       42.82%   42.82%           
===========================================
  Files             102      102           
  Lines           35860    35860           
===========================================
  Hits            15358    15358           
  Misses          20502    20502           

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data'

Translated to English:

Δ = absolute <relative> (impact), ø = not affected, ? = missing data'
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