Resolve "[origin import] legend read as annotation, memory corruption"

Description

The new test ProjectImportTest::testOriginMultiLayersAsCoordinateSystemsWithLegend() added in this can be used to reproduce the bad memory access in liborin which is fixed with Miquel's patch added in the second commit in this MR.

Conformity

• Changelog entry
• Unit tests
• Update INSTALL
• Downport
• Fixes:

When external dependencies are removed

• Reporting to ...

Closes #838 (closed)