cmake: tweak download command line

[benoit-pierre]

To work around MuPDF' slow server:

• increase connection timeout and maximum allowed total time
• drop curl builtin retries: we already manually retrying 2 times anyway (in case of possible incorrect checksum)

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This change is 

[Frenzie]

Wasn't there some fallback mechanism?
https://github.com/ArtifexSoftware/mupdf-downloads/releases

[benoit-pierre]

Wasn't there some fallback mechanism? https://github.com/ArtifexSoftware/mupdf-downloads/releases

Nope! I missed that (I follow https://github.com/ArtifexSoftware/mupdf/releases.atom in my RSS reader, which only has the automatically generated source artifacts, sans sub-modules).

[Frenzie]

Close this one with #2218 in place?

[benoit-pierre]

I don't know, I think it still make sense if a mirror is particularly slow. Plus there's no need for retrying within individual curl calls if we do retry ourselves anyway (and potentially alternate with a fallback).

[benoit-pierre]

The increased timeout might make things a little slower… ¯\(ツ)/¯

[Frenzie]

10 already seems quite long is the main thing I was referring to. There's no need to curl retry.

[benoit-pierre]

I can't currently download from https://casper.mupdf.com/downloads/archive/mupdf-1.26.11-source.tar.lz with a connect timeout of 10, it takes 14 seconds for the connection to be established… (Plus max-time at 30s was also to slow, but my current connection is also not particularly fast).

[Frenzie]

I'm surprised it would start at 14 if it didn't at 10, but I can confirm that it currently starts after some 13-14 seconds. (It does seem to finish nearly instantaneously for me.)