My previous test (commit 41285813) was a bit misinformed. So it turns
out bug #4185 is for all platforms and the broken libheif versions are
1.5.0 and 1.5.1 only.

So my new test (platform independent) is: prefer libheif versions with
profile support, except 1.5.x; then prefer lower versions without
profile support; and only as last resort accept 1.5.x versions (but
output a warning).