CONFIG       += svg link_pkgconfig
PKGCONFIG    += gtk+-3.0 appindicator3-0.1 glib-2.0

These are reporting unknown file or directory -> #include <gtk/gtk.h>
#include <gio/gio.h>
#include <libappindicator/app-indicator.h>

This is the error
/usr/include/glib-2.0/gio/gio.h:54: In file included from /usr/include/glib-2.0/gio/gio.h:54:0,