build: Add configure option to enable -Bsymbolic

We should always compile with -Bsymbolic enabled to avoid intra-library
PLT jumps.

https://bugzilla.gnome.org/show_bug.cgi?id=703734
(cherry picked from commit a9327484746820a5a2b8c1acf4a78470b004f0a0)

Signed-off-by: Emmanuele Bassi <ebassi@gnome.org>
path: Check if JSONPath expression is NULL

https://bugzilla.gnome.org/show_bug.cgi?id=708318
Release JSON-GLib 0.16.2
Post-release version bump to 0.16.3