Removed invalid block face handling code

The code for handling invalid block faces is removed by gcc and clang as it is undefined behavior for a enum
to contain a value that is not part of the enum. Since the only way that the line can be executed is through
undefined behavior clang and gcc remove it so the function fits in the caches better.

src/Defines.h

@@ -290,7 +290,6 @@ inline AString BlockFaceToString(eBlockFace a_BlockFace)
 		case BLOCK_FACE_ZP: return "BLOCK_FACE_ZP";
 		case BLOCK_FACE_NONE: return "BLOCK_FACE_NONE";
 	}
-	return Printf("Unknown BLOCK_FACE: %d", a_BlockFace);
 }