[Bug c/21420] [3.4/4.0/4.1 Regression] Accepts writting to const via asm

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.0.0 3.4.0 4.0.0
      Known to work|                            |3.3.3
   Target Milestone|---                         |3.4.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21420