add blank material files

valve/pbr/halflife.wad/-FIFT_WALL13/-FIFT_WALL13.mat

@@ -0,0 +1,8 @@
+
+{
+"for" "-0FIFT_WALL13"
+//"basecolor_map" "-0FIFT_WALL13.png"
+//"normal_map" "-0FIFT_WALL13_normal.png"
+//"metal_map" "-0FIFT_WALL13_metal.png"
+//"roughness_map" "-0FIFT_WALL13_roughness.png"
+}