Preserve the SDK images between upgrades
Preserve the SDK images between upgrades

The `android` tool downloads the SDK images into its prefix. Which means you have to move them manually to the new android-sdk keg when you upgrade. Which sucks. So we'll store them in the var/lib/android-sdk directory because that makes the most sense based on my interpretation of the POSIX filesystem hierarchy documentation.

We still have to symlink the var directories back into the keg, because the SDK is stupid.

For discussion: whether we should use var in this manner more.

nandub/homebrew-core,lemzwerg/homebrew-core,andyjeffries/homebrew-core,ilovezfs/homebrew-core,zyedidia/homebrew-core,zmwangx/homebrew-core,mbcoguno/homebrew-core,moderndeveloperllc/homebrew-core,grhawk/homebrew-core,j-bennet/homebrew-core,BrewTestBot/homebrew-core,FinalDes/homebrew-core,uyjulian/homebrew-core,sjackman/homebrew-core,smessmer/homebrew-core,aabdnn/homebrew-core,robohack/homebrew-core,kuahyeow/homebrew-core,maxim-belkin/homebrew-core,jvillard/homebrew-core,bcg62/homebrew-core,nbari/homebrew-core,LinuxbrewTestBot/homebrew-core,sjackman/homebrew-core,makigumo/homebrew-core,straxhaber/homebrew-core,JCount/homebrew-core,aren55555/homebrew-core,mvitz/homebrew-core,jabenninghoff/homebrew-core,FinalDes/homebrew-core,lembacon/homebrew-core,mbcoguno/homebrew-core,edporras/homebrew-core,dsXLII/homebrew-core,spaam/homebrew-core,andyjeffries/homebrew-core,mvbattista/homebrew-core,bigbes/homebrew-core,stgraber/homebrew-core,chrisfinazzo/homebrew-core,bfontaine/homebrew-core,mvitz/homebrew-core,bcg62/homebrew-core,mbcoguno/homebrew-core,wolffaxn/homebrew-core,LinuxbrewTestBot/homebrew-core,Linuxbrew/homebrew-core,kunickiaj/homebrew-core,aren55555/homebrew-core,sdorra/homebrew-core,straxhaber/homebrew-core,fvioz/homebrew-core,rwhogg/homebrew-core,jdubois/homebrew-core,kunickiaj/homebrew-core,passerbyid/homebrew-core,adam-moss/homebrew-core,nbari/homebrew-core,fvioz/homebrew-core,cblecker/homebrew-core,battlemidget/homebrew-core,jvehent/homebrew-core,dsXLII/homebrew-core,rwhogg/homebrew-core,DomT4/homebrew-core,mvitz/homebrew-core,jvillard/homebrew-core,adamliter/homebrew-core,reelsense/homebrew-core,battlemidget/homebrew-core,cblecker/homebrew-core,forevergenin/homebrew-core,Linuxbrew/homebrew-core,uyjulian/homebrew-core,mahori/homebrew-core,filcab/homebrew-core,Homebrew/homebrew-core,git-lfs/homebrew-core,phusion/homebrew-core,jdubois/homebrew-core,Homebrew/homebrew-core,grhawk/homebrew-core,bcg62/homebrew-core,mfikes/homebrew-core,kuahyeow/homebrew-core,lembacon/homebrew-core,zyedidia/homebrew-core,maxim-belkin/homebrew-core,robohack/homebrew-core,edporras/homebrew-core,Moisan/homebrew-core,ShivaHuang/homebrew-core,j-bennet/homebrew-core,forevergenin/homebrew-core,lasote/homebrew-core,git-lfs/homebrew-core,BrewTestBot/homebrew-core,tkoenig/homebrew-core,DomT4/homebrew-core,ylluminarious/homebrew-core,jvillard/homebrew-core,lembacon/homebrew-core,stgraber/homebrew-core,lasote/homebrew-core,adam-moss/homebrew-core,filcab/homebrew-core,moderndeveloperllc/homebrew-core,mvbattista/homebrew-core,jabenninghoff/homebrew-core,aabdnn/homebrew-core,jdubois/homebrew-core,wolffaxn/homebrew-core,phusion/homebrew-core,gserra-olx/homebrew-core,gserra-olx/homebrew-core,ilovezfs/homebrew-core,adamliter/homebrew-core,JCount/homebrew-core,Moisan/homebrew-core,mfikes/homebrew-core,zmwangx/homebrew-core,lemzwerg/homebrew-core,tkoenig/homebrew-core,jvehent/homebrew-core,ylluminarious/homebrew-core,chrisfinazzo/homebrew-core,bigbes/homebrew-core,wolffaxn/homebrew-core,passerbyid/homebrew-core,spaam/homebrew-core,nandub/homebrew-core,ShivaHuang/homebrew-core,smessmer/homebrew-core,mahori/homebrew-core,bfontaine/homebrew-core,makigumo/homebrew-core,reelsense/homebrew-core,sdorra/homebrew-core