Log Message:
json-glib: update to 1.4.4.

Switch to meson build system.  Based on wip/json-glib.

Overview of changes for 1.4
==============================
• Use Meson as the only build system
• #773504 - Avoid extra allocations [Garrett Regier]
• #780550 - meson error looking for python3 [Daniele Forghieri]
• #769206 - docs: Clarify when NULL might be returned [Matthew Leeds]
• #766281 - utils/json_from_string: Don't reset user-provided error
            argument [Heinrich Fink]
• #758580 - json_reader_is_value returns TRUE for null type but
            json_reader_get_value throws an error [Robert Ancell]
• #768788 - Incorrect account of jsonPath syntax in doc [Allin Cottrell]
• #774688 - json_from_string() could be optimized to avoid copying the
            root node [Ole André Vadla Ravnås]