C4Section: Don't load the material enumeration and reinitialize the t…

…exture map

if the materials and textures were copied from another section

This allows `CPattern` to reuse the cached patterns, massively cutting down
on RAM costs - with 2000 20x20 sections, 10 GB of RAM were previously used
just for cached patterns.

src/C4Section.cpp

@@ -230,16 +230,16 @@ bool C4Section::InitMaterialTexture(C4Section *const fallback)
 		// Logs
 		LogF(LoadResStr("IDS_PRC_TEXTURES"), tex_count);
 		LogF(LoadResStr("IDS_PRC_MATERIALS"), mat_count);
-	}
 
-	// Load material enumeration
-	if (!Material.LoadEnumeration(Group))
-	{
-		LogFatal(LoadResStr("IDS_PRC_NOMATENUM")); return false;
-	}
+		// Load material enumeration
+		if (!Material.LoadEnumeration(Group))
+		{
+			LogFatal(LoadResStr("IDS_PRC_NOMATENUM")); return false;
+		}
 
-	// Initialize texture map
-	TextureMap.Init();
+		// Initialize texture map
+		TextureMap.Init();
+	}
 
 	// Cross map mats (after texture init, because Material-Texture-combinations are used)
 	Material.CrossMapMaterials();