icon-validator: Don't make flatpak_get_bwrap() extern
icon-validator: Don't make flatpak_get_bwrap() extern

The Meson build files that I'm working on enable more compiler warnings
by default than Autotools does, and in particular -Wmissing-declarations
complains about global functions that are not predeclared. There's no
need for this one to be global.

Signed-off-by: Simon McVittie <0e1aea601907c1a85c2dc96e5ea37e23c58d2e9b@collabora.com>

flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak