include paths: -I vs -isystem

[kkaefer]

I'm seeing many custom packages that specify the same path both in -I and -isystem. Is there a particular reason to do that?

In https://github.com/mapbox/mason/blob/master/mason.sh#L496, we are removing the prefix from there and call uniq to remove adjacent duplicates.

/cc @springmeyer @artemp

[springmeyer]

No reason that I'm aware of. Can you point to an example package that does this?

[kkaefer]

https://github.com/mapbox/mason/search?utf8=✓&q=isystem