- Use the correct, upstream provided tarball.

- update to version 20.10.0:
+ core:
- Filter out repeated forms.
- Implement EmbedStream::reset().
- CairoOutputDev: evict just font faces owned solely by cache.
- Splash: Rename Yd to Ydown, Xu to Xup, etc.
- Splash: fix crash in out-of-memory situation.
- Fix some undefined behaviour situation with forged files.
- Compability fix for Forms.
- Fix fetching of Objects failing in some cases.
- Fix clearing date in Annot setModified/setDate.
- TextSelectionPainter: support glyphless fonts.
- Splash: Don't try read past end of image.
- avoid abort() on large memory allocation.
- Fix memory leak on broken files.
- Fix potential invalid memory read.
- Small code improvements.
- Sub-page objects: initialize clip max values considering the
render resolution.
- Splash: Set initial line width to 1.
- Fix stack overflow with specially crafted files.
- GfxShading: Simplify holding the Function.
- Splash: Fix x86 + windows asm build.
- Fix regression on PS conversion..
Regression only happened on applications that are locale
enabled i.e. Okular but not pdftops, when using a quite new
lcms and the user locale uses , as decimal separator instead
of .