Move mlton, mlkit, urweb to the boneyard.
Move mlton, mlkit, urweb to the boneyard.

mlton is a binary-only formula that only works when installed
to /usr/local. Moving it, and things that depend on it to the
boneyard.

Closes Homebrew/homebrew#21780.

mahori/brew,palxex/brew,AnastasiaSulyagina/brew,staticfloat/brew,DomT4/brew,aw1621107/brew,aw1621107/brew,ilovezfs/brew,amar-laksh/brew_sudo,amar-laksh/brew_sudo,muellermartin/dist,rwhogg/brew,jmsundar/brew,Homebrew/brew,bfontaine/brew,vitorgalvao/brew,pseudocody/brew,mahori/brew,muellermartin/dist,gordonmcshane/homebrew,vitorgalvao/brew,mgrimes/brew,nandub/brew,staticfloat/brew,EricFromCanada/brew,DomT4/brew,toonetown/homebrew,mgrimes/brew,nandub/brew,alyssais/brew,tonyg/homebrew,zmwangx/brew,sjackman/homebrew,konqui/brew,gregory-nisbet/brew,mahori/brew,EricFromCanada/brew,claui/brew,rwhogg/brew,rwhogg/brew,palxex/brew,sjackman/homebrew,claui/brew,reitermarkus/brew,gregory-nisbet/brew,DomT4/brew,pseudocody/brew,jmsundar/brew,zmwangx/brew,Homebrew/brew,toonetown/homebrew,muellermartin/dist,reelsense/brew,JCount/brew,gordonmcshane/homebrew,sjackman/homebrew,mistydemeo/homebrew,vitorgalvao/brew,palxex/brew,reelsense/brew,MikeMcQuaid/brew,maxim-belkin/brew,mahori/brew,AnastasiaSulyagina/brew,MikeMcQuaid/brew,hanxue/linuxbrew,vitorgalvao/brew,claui/brew,bfontaine/brew,reitermarkus/brew,EricFromCanada/brew,reelsense/brew,Homebrew/brew,MikeMcQuaid/brew,reitermarkus/brew,pseudocody/brew,nandub/brew,tonyg/homebrew,mgrimes/brew,konqui/brew,Linuxbrew/brew,sjackman/homebrew,JCount/brew,hanxue/linuxbrew,JCount/brew,tonyg/homebrew,reitermarkus/brew,MikeMcQuaid/brew,EricFromCanada/brew,ilovezfs/brew,maxim-belkin/brew,mistydemeo/homebrew,AnastasiaSulyagina/brew,amar-laksh/brew_sudo,konqui/brew,Linuxbrew/brew,mistydemeo/homebrew,ilovezfs/brew,maxim-belkin/brew,toonetown/homebrew,gregory-nisbet/brew,aw1621107/brew,konqui/brew,alyssais/brew,Linuxbrew/brew,alyssais/brew,DomT4/brew,bfontaine/brew,nandub/brew,staticfloat/brew,Homebrew/brew,jmsundar/brew,gordonmcshane/homebrew,Linuxbrew/brew,claui/brew,zmwangx/brew,hanxue/linuxbrew,JCount/brew