Replace gcc dependency with libomp

[SeekingMeaning]

See https://github.com/brewsci/homebrew-bio/search?q=%22needs+openmp%22

Formula	PR	Merged?
arcs
arks
biobloomtools
bracken
canu
cd-hit	#1141	✅
centrifuge
dida
discovardenovo
e-mem	#1142	✅
ema
fastani	#1088	✅
fasttree	#1123	✅
gappa
genome-painter	#1143	✅
gfakluge
ghostz	#1140	✅
hh-suite
idba
iqtree
iqtree2
kraken
kraken2
megahit
metabat
mpboot
nanopolish
ngmerge
ntcard
ntedit
nthits
parasail
parsnp	#1107	✅
phlawd	#1018	✅
racon	#1105	✅
stacks
star-aligner	#1098	✅
treepl	#900	✅
trinity
viennarna
wish

[stale]

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