ls: cache file_type() call in get_block_size

Author: sylvestre

src/uu/ls/src/ls.rs

@@ -2849,7 +2849,8 @@ fn get_block_size(md: &Metadata, config: &Config) -> u64 {
     */
     #[cfg(unix)]
     {
-        let raw_blocks = if md.file_type().is_char_device() || md.file_type().is_block_device() {
+        let ft = md.file_type();
+        let raw_blocks = if ft.is_char_device() || ft.is_block_device() {
             0u64
         } else {
             md.blocks() * 512