[json-glib] Non-fast-forward update to branch coverity-leak

[Ray Strode <halfline src gnome org>]

The branch 'coverity-leak' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  b13f25e... builder: Don't leak memory if json_builder_get_root fails s

Commits added to the branch:

  e4e42b1... builder,parser: Use g_assert for sanity checks