tcg/TODO

   1 - Add new instructions such as: clz, ctz, popcnt.
   2
   3 - See if it is worth exporting mul2, mulu2, div2, divu2.
   4
   5 - Support of globals saved in fixed registers between TBs.
   6
   7 Ideas:
   8
   9 - Move the slow part of the qemu_ld/st ops after the end of the TB.
  10
  11 - Change exception syntax to get closer to QOP system (exception
  12   parameters given with a specific instruction).
  13
  14 - Add float and vector support.