Duplicate symbols when statically linking avro and spatial

[NiclasHaderer]

At MotherDuck, we build and statically link DuckDB extensions on our server. Since Iceberg has a dependency on Avro, we also have to like the Avro extension on the server. Unfortunately, this leads to a conflict for duplicate symbols, namely json_object_get when linking both duckdb-spatial and duckdb-avro.

This issue stems from the inclusion of the jansson library in avro and the gdal library in spatial.

Both libraries define a jsob_object_get function (see https://github.com/akheron/jansson/blob/96d160df90016066d04d493d1d69639474ba4f20/src/jansson.h#L189 and https://github.com/OSGeo/gdal/blob/9c6652c257799b88ca83302c3368545aba869c65/ogr/ogrsf_frmts/geojson/libjson/json_object.h#L348).

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This PR patches the json_object_get function in gdal by renaming it to gdal__json_object_get.

[Maxxen]

Thanks for the PR! Dont worry about failing CI, I need to apply patches from DuckDB main, but I can take it from here!

[NiclasHaderer]

Thanks a lot