Add a right shift mapping

This saves less bytes - by far - and is likely not the best operator to choose.
But for now, it works -- a better choice may arise later.

Alphabetic     : 2538 bytes   (- 84 bytes)
Case_Ignorable : 1773 bytes   (- 30 bytes)
Cased          : 790 bytes    (- 18 bytes)
Cc             : 26 bytes     (-  6 bytes)
Grapheme_Extend: 1490 bytes   (- 18 bytes)
Lowercase      : 865 bytes    (- 36 bytes)
N              : 1040 bytes   (- 24 bytes)
Uppercase      : 778 bytes    (- 60 bytes)
White_Space    : 85 bytes     (-  6 bytes)
Total table sizes: 9385 bytes (-282 bytes)

src/libcore/unicode/mod.rs

@@ -66,12 +66,12 @@ fn range_search<
     } else {
         let (real_idx, mapping) = bitset_canonicalized[idx - CANONICAL];
         let mut word = bitset_canonical[real_idx as usize];
-        let should_invert = mapping & (1 << 7) != 0;
+        let should_invert = mapping & (1 << 6) != 0;
         if should_invert {
             word = !word;
         }
         // Unset the inversion bit
-        let rotate_by = mapping & !(1 << 7);
+        let rotate_by = mapping & !(1 << 6);
         word = word.rotate_left(rotate_by as u32);
         word
     };