bazel on darwin should mark output_base and output_user_root to not be backed up by Time Machine

[dmaclach]

currently output_base and output_user_root are by default going to be backed up by Time Machine, and this is not good. The fact that they are writing into var/tmp by default is saving most users right now (var/tmp is not backed up) but anybody who specifies their own options is going to get hit by this.

Please assign to me.

[kchodorow]

Actually, @dslomov pointed out that if you're providing the directory, it's a bit weird to have Bazel change it's semantics for you.

[dmaclach]

Xcode by default marks its output directories as not being backed up. All of this data can be regenerated so it doesn't make sense to be backing up gigs of build files IMHO

[ulfjack]

Looks like this was fixed. Closing.