ppa is missing build flag, leading to crashes

Summary:

As found out by @KrIr17 in inbox#9327 (comment 1588340458) .

This leads to multiple different crashes, as the ppa seems to automatically be falling back to the 'debug' build flag.

Steps to reproduce:

• use official Inkscape from ppa

What happened?

• crashes that do not happen in other builds, e.g.
  • #2993
  • (related: #2448 )
  • inbox#7424 (comment 1055656784)

What should have happened?

• just the 'normal' crashes ... ;-)

Version info

Inkscape 1.3 from ppa, also affected 1.2.x, 1.1.x.

Tagging @marcjeanmougin