build: Build GVDB as a Meson subproject

Since recently, GVDB repository includes a minimal meson.build
file to allow building as a subproject without additional
hassles (e.g. shipping supporting files at /subprojects/repofiles/)
Drop our internal copy of GVDB in favor of a subproject built
through Meson.

Since we're updating many years across, there has been GVDB API
updates that we need to adapt to: GvdbTable is no longer a refcounted
object, and gvdb_table_walk() is no longer offered to iterate across
values.

These largely affect our own set of GVDB tests though, the test
for gvdb_table_walk() was dropped, and so is the ref/unref one
(it basically does the same than gvdb/flat_strings, after dropping
the refcounting). These remaining tests stay useful, and should
ideally move into the GVDB repository, so it can run as a separate
suite here.

1 files changed, 6 insertions, 0 deletions

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 000000000..259754f84
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,6 @@
+[submodule "subprojects/gvdb"]
+	path = subprojects/gvdb
+	url = https://gitlab.gnome.org/GNOME/gvdb.git
+	branch = 0854af0fdb6d527a8d1999835ac2c5059976c210
+	shallow = true
+