boxing_nan.h: remove false description in the comment [ci skip]
Ref
@@ -36,8 +36,6 @@ enum mrb_nanbox_tt_inline {
* ptr : 01111111 11111100 PPPPPPPP PPPPPPPP PPPPPPPP PPPPPPPP PPPPPPPP PPPPPP01
* Stored as O = R + 0x8004000000000000, retrieved as R = O - 0x8004000000000000.
* This makes pointers have all zeros in the top 32 bits.
- * Small-ints and strs have 1 as LSB to make sure they don't look like pointers
- * to the garbage collector.
*/
typedef struct mrb_value {
uint64_t u;
