Apparently github.com/google/licenseclassifier/tools/identify_license
doesn't like that LICENSE is missing.
Merging the two separate license files makes one less file, and by adding the
SPDX identifier at the top I believe there is even less ambiguity that Gio
is covered by the UNLICENSE as well as the MIT license, as described in
the README.md file.
Signed-off-by: Elias Naur <mail@eliasnaur.com>