Cleanup coverage
Cleanup coverage

This splits the coverage task out by adding “precoverage” and
“postcoverage”.  It also deletes the intermediate coverage files once
it is done.

coderhaoxin/jade,Laoujin/jade,bogus34/jade-vfs,webmasteraxe/jade,ceremcem/jade,rajnishyadav321/jade,jadejs/then-jade,gdibble/jade,omixen/jade,webskyer/jade,omixen/jade,jjz/jade,andreytkachenko/jade,Shinchy/jade,coderhaoxin/jade,VeraWei/jade,cesarmarinhorj/jade,webskyer/jade,martindale/jade,jjz/jade,bogus34/jade-vfs,Mitrend/jade,modulexcite/jade,webmasteraxe/jade,cesarmarinhorj/jade,mrotaru/jade,magicdawn/jade,cgvarela/jade,fredyteheranto/jade,mrotaru/jade,muthhus/jade,fredyteheranto/jade,gexiaowei/jade,mumaoxi/jade,hnag409/jade,Victorgichohi/jade,muthhus/jade,pugjs/pug,ridixcr/jade,gexiaowei/jade,tranhieutt/jade,angryrobot/jade,VANITAX/jade,angryrobot/jade,andreytkachenko/jade,jirengu/jade,pugjs/jade,pugjs/then-jade,Laoujin/jade,illusionfield/jade,VANITAX/jade,Victorgichohi/jade,colin-h/jade,hnag409/jade,ilovezy/jade,Shinchy/jade,jodytate/jade,martindale/jade,modulexcite/jade,mumaoxi/jade,Mitrend/jade,angrilove/jade,ilovezy/jade,pugjs/then-jade,cutsin/jade,pugjs/pug,illusionfield/jade,cgvarela/jade,cutsin/jade,colin-h/jade,rajnishyadav321/jade,gdibble/jade,ridixcr/jade,jadejs/then-jade,pugjs/jade,angrilove/jade,jirengu/jade,harp/jade,magicdawn/jade,harp/jade,VeraWei/jade,tranhieutt/jade,jodytate/jade