Migrate to new `cfg` attribute syntax`
Migrate to new `cfg` attribute syntax`

anchovieshat/num,rust-num/num-traits,DonSheddow/num,tomaka/num,huonw/num,rust-num/num,Ticki/num,bluss/num,rust-num/num-bigint,anchovieshat/num,ollie27/rust_num,rust-num/num-integer,DonSheddow/num,koverstreet/num,achanda/num,Gustorn/num,vks/num,rust-num/num,jbcrail/num,rust-num/num-integer,vks/num,Emerentius/num,rust-lang/num,koverstreet/num,jdm/num,rust-num/num-bigint,rust-lang/num,jbcrail/num,hauleth/num,achanda/num,rust-num/num-traits