[syslog-ng] [PATCH 0/7] value-pairs dot notation walker

[Gergely Nagy]

The patches that will follow this overview soon implement a 'walker'
for value-pairs, a way to walk the internal flat structure syslog-ng
uses as if it was a tree. This is important for two modules in
particular: $(format-json) and the mongodb destination.

The latter already supportes storing structured data, but it is using
upserts (with all its downsides) to accomplish that. The former - up
until now - was only able to format flat JSON.

With these patches, both change: $(format-json) becomes able to emit
structured data, and the mongodb destination starts to use inserts.

The patches also merge the tfjson and jsonparser modules into a single
json module, and implements our own JSON formatting for
$(format-json). This means that json-glib support is completely
removed, as it became unnecessary, and json-c is only used by the
parser, but for practical reasons, required to build the plugin. That
is, it is no longer possible to build $(format-json) only, but not
json-parser, nor the other way around.

The final patch is a bonus, that corrects a small error in jsonparser,
and stops it from emitting an assertion warning on stderr in certain
cases.