Fix for Intel compiler bug

[hroptatyr]

Closes #3647
Calculate skip condition after and separate from key counting.

[codecov]

Codecov Report

Merging #3648 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3648      +/-   ##
==========================================
- Coverage   98.25%   98.25%   -0.01%     
==========================================
  Files          69       69              
  Lines       13088    13087       -1     
==========================================
- Hits        12860    12859       -1     
  Misses        228      228

Impacted Files	Coverage Δ
src/forder.c	99.71% <100%> (-0.01%)	⬇️

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[mattdowle]

Great, thanks for the report and fix. I'll just add a minor tweak, a news item, and merge.

[mattdowle]

This was a code contribution, so I'm sorry @hroptatyr, I should have added you to DESCRIPTION as a contributor at the time. I'll correct my mistake now in a commit to master linking to this PR.
Found as a result of following up on discussion at the end of #1236.
(This contribution was after the license change from GPL to MPL so it doesn't need to be included in the forthcoming retrospective-permission PR.)