formula_installer: don't always post_install.
formula_installer: don't always post_install.

We don't want to do so when building bottles or we can end up with some weird stuff being bottled unintentionally (and it'll run twice; once before bottling, once afterwards).

Fixes Homebrew/homebrew#34349.

Closes Homebrew/homebrew#34397.

Signed-off-by: Mike McQuaid <a17fed27eaa842282862ff7c1b9c8395a26ac320@mikemcquaid.com>

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