libtracker-data: Convert coalesced elements to string

Dropping that possibly fixes coalescing of URNs and datetimes with
other types transparently handled by SQLite. Eg. this broke the
"tracker search" CLI subcommand, where it uses:

  SELECT COALESCE(nie:url(?u), ?u) ...

This resulted in "tracker search foo" returning "(null)" as the
file uri/urn.

We must translate each Expression to string so that correctly results
in the URL string being coalesced with the URN string. This is the
expected result, and a regression compared to the older parser.

0 files changed, 0 insertions, 0 deletions