Auto merge of #5048 - justjavac:patch-1, r=llogiq
Auto merge of #5048 - justjavac:patch-1, r=llogiq

update license year to 2020

Happy new year 2020

changelog: none

graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust