create-highcontrast: process only symbolic icons
create-highcontrast: process only symbolic icons

Since the switch from gnome-icon-theme-symbolic to adwaita-icon-theme,
this tool has been inadvertently processing non-symbolic icons.

https://bugzilla.gnome.org/show_bug.cgi?id=740444

DoctorJellyface/gnome-themes-standard,Distrotech/gnome-themes-standard,DoctorJellyface/gnome-themes-standard,Distrotech/gnome-themes-standard