Add gitignore for build and install directories

[viktorku]

The build and install directories should not pollute the git workspace.

[taketwo]

See #745.
Though maybe we can revise that decision. E.g. OpenCV does have build in the ignore list.

[SergioRAgostinho]

Those folders don't exist in our repo, that's on the user side so I'm not sure it makes sense to add it our gitignore. I think this PR is unnecessary.

[taketwo]

I would speculate that 99% use build directory, whereas the percentage of those who know about .git/info/exclude and can "locally" ignore a directory is way lower. So many people end up having "dirty" state in their repos.

Are there any serious arguments against having build in the global .gitignore?

[SergioRAgostinho]

Are there any serious arguments against having build in the global .gitignore?

Not from my side.

[jspricke]

-1 from me, Just ad it locally if it enoyes you.

[viktorku]

those who know about .git/info/exclude and can "locally" ignore a directory

If an open source project creates additional artifacts by compilation with default flags, and those are not supposed to be included in the repo, what is the problem by ignoring them? That is by definition the purpose of .gitignore.

Why does every potential contributor have to manually dabble in the repo's .git exclusion settings after each fork/clone to ignore something that should have been ignored out-of-the-box?

[jspricke]

Because these names are completely arbitrary and don't need to be in the source folder.

[SergioRAgostinho]

Can I close this? I agree with @jspricke on this, the user decides where he wants to build the cache and install it, and since this is can be completely arbitrary, it doesn't make sense to specify these folders in the git ignore.