odg export: stroke width incorrect

Split out from #3560 , might also be mentioned in https://bugs.launchpad.net/inkscape/+bug/474956 (which is a mega-issue)

Steps to reproduce:

• download test-stroke-width.svg (file with a path with a stroke-width
• inkscape --export-type=odg test-stroke-width.svg

What happened?

• Stroke not exported at correct width (left and right objects should be same size)

png export	odg export	libreoffice import of svg
	test-stroke-width.odg	test-stroke-width_libre.odg

comprehensive test file from linked issue: test.2017_04_26_inkscape.svgz

comprehensive test file from launchpad issue: bounding_line4.svg

What should have happened?

• Stroke width exported at correct size

Workaround: libreoffice's svg import is pretty good.

Version Info:

• Inkscape 1.1-dev (c401a8e72c, 2020-11-05) Linux Mint 20