Do not print newline after functor declaration

[mbid]

For other declarations, e.g. relations or types, we don't print newlines, so we probably also don't want it for functors.

[codecov]

Codecov Report

Merging #2179 (2fa0494) into master (ab8929f) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2179      +/-   ##
==========================================
- Coverage   75.55%   75.54%   -0.01%     
==========================================
  Files         452      452              
  Lines       27249    27248       -1     
==========================================
- Hits        20587    20585       -2     
- Misses       6662     6663       +1     

Impacted Files	Coverage Δ
src/ast/FunctorDeclaration.cpp	38.09% <ø> (+1.73%)	⬆️
...ouffle/datastructure/ConcurrentInsertOnlyHashMap.h	88.18% <0.00%> (-1.82%)	⬇️
src/include/souffle/utility/ParallelUtil.h	83.72% <0.00%> (-1.56%)	⬇️
src/include/souffle/datastructure/BTree.h	97.47% <0.00%> (+0.42%)	⬆️

[b-scholz]

Thanks for the contribution