add blank material files

bshift/pbr/barney.wad/+_coolant/+_coolant.mat

@@ -0,0 +1,8 @@
+
+{
+"for" "+0_coolant"
+//"basecolor_map" "+0_coolant.png"
+//"normal_map" "+0_coolant_normal.png"
+//"metal_map" "+0_coolant_metal.png"
+//"roughness_map" "+0_coolant_roughness.png"
+}