Change CPPEXTPATH to CPPPATH for mesa_private_inc_paths

[TCROC]

Just another PR to consider alongside #106413.

Fixes: #106376

Hopefully this doesn't bring back the warnings that the other PR does and we get to have our cake and eat it to! :)

[TCROC]

@akien-mga CC

🤞 this one doesn't bring it all those warnings. And pray the cosmic rays don't ruin our day.

[TCROC]

That's interesting... why don't I encounter these errors when building on my local?

[akien-mga]

That's the same thing I did in #106413, minus some cosmetic cleanup. It does bring back the warnings sadly.

[akien-mga]

That's interesting... why don't I encounter these errors when building on my local?

You probably don't build with warnings=extra werror=yes like the CI does.

[TCROC]

Ah I see. I'll still test your PR tho to confirm that it works (or doesn't) :)

[akien-mga]

To clarify, my PR has two commits:

• The first is the same as yours, and introduced warnings
• The second tries another approach by keeping CPPEXTPATH but changing the order

[TCROC]

Ah I see... I'm testing the 2nd commit now then :). Was confused at first but that makes much more sense :)

[TCROC]

Hey @akien-mga. Which PR between ours are you wanting to go with? I don't mind which. I'm just not sure what to do to make the pipeline happy.