[libtiff] use builtin as backup so that tiff can be always part of asimage

[ferdymercury]

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[github-actions]

Test Results

    15 files      15 suites   2d 6h 2m 50s ⏱️
 3 811 tests  3 811 ✅ 0 💤 0 ❌
51 152 runs  51 152 ✅ 0 💤 0 ❌

Results for commit b97aa10.

[dpiparo]

This PR is good work. Is anybody needing to generate natively tiff images? The discussion is still open if gif needs to be supported after 6.40...

[ferdymercury]

Thanks!

Is anybody needing to generate natively tiff images?

Not me at the moment, but having an extra ROOT build option assymmetric from png jpeg bmp gif seems weird. Here we remove one ROOT build option at the price of a builtin backup (that seems reasonably easy). This way functionality will be more reproducible in case someone was using asimage_tiff locally but not present in binaries or so.

The discussion is still open if gif needs to be supported

In my opinion, saving as gif still makes sense when you want to do animated videos via TCanvas::SaveAs(c.gif++NN) that you can easily include in any webpage or in a PPT. Unless there is an alternative way of generating those :)