/usr/include/KF5/AkonadiSearch/ is in libkf5akonadisearch-dev 16.04.3-1+b2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/AkonadiSearch/Debug/
/usr/include/KF5/AkonadiSearch/Debug/akonadisearchdebugdialog.h
/usr/include/KF5/AkonadiSearch/Debug/akonadisearchdebugsearchpathcombobox.h
/usr/include/KF5/AkonadiSearch/Debug/search_debug_export.h
/usr/include/KF5/AkonadiSearch/PIM/
/usr/include/KF5/AkonadiSearch/PIM/collectionquery.h
/usr/include/KF5/AkonadiSearch/PIM/contactcompleter.h
/usr/include/KF5/AkonadiSearch/PIM/contactquery.h
/usr/include/KF5/AkonadiSearch/PIM/emailquery.h
/usr/include/KF5/AkonadiSearch/PIM/notequery.h
/usr/include/KF5/AkonadiSearch/PIM/query.h
/usr/include/KF5/AkonadiSearch/PIM/resultiterator.h
/usr/include/KF5/AkonadiSearch/PIM/search_pim_export.h