Fix build when RGB_{RED,GREEN,BLUE}!={0,1,2}

Broken by aa7459050d

rdppm.c

@@ -660,8 +660,9 @@ start_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
     } else if (maxval == MAXJSAMPLE && sizeof(JSAMPLE) == sizeof(U_CHAR) &&
                (cinfo->in_color_space == JCS_EXT_RGB
 #if RGB_RED == 0 && RGB_GREEN == 1 && RGB_BLUE == 2 && RGB_PIXELSIZE == 3
-                || cinfo->in_color_space == JCS_RGB)) {
+                || cinfo->in_color_space == JCS_RGB
 #endif
+               )) {
       source->pub.get_pixel_rows = get_raw_row;
       use_raw_buffer = TRUE;
       need_rescale = FALSE;