It would be great if Linux Libertine could include the mkmk OT feature. The official definition is:
"The 'mkmk' feature positions mark glyphs in relation to another mark glyph. This feature may be implemented as a MarkToMark Attachment lookup (GPOS LookupType = 6). "
It probably needs to be added to most or all diacritics in the "Combining Diacritical Marks" range. I have noticed it missing in:
1. U+0301: ́ COMBINING ACUTE ACCENT
2. U+030A: ̊ COMBINING RING ABOVE