Patch ping

[Jakub Jelinek]

- PR55137 fold reassociation fix                                                
                                                                 
  http://gcc.gnu.org/ml/gcc-patches/2012-11/msg00636.html                       
                                                                 
  (alternatively also retry with unsigned atype if the reassociation            
                                                                 
  would fail otherwise)                                                         
                                                                 

- PR43631 fix up var-tracking notes in between bbs
  http://gcc.gnu.org/ml/gcc-patches/2012-11/msg01201.html

- PR55331 substitute_and_fold fix for memmove folding to nothing
  http://gcc.gnu.org/ml/gcc-patches/2012-11/msg01302.html

- convert asan to use builtins instead of building fndecls on the fly
  http://gcc.gnu.org/ml/gcc-patches/2012-11/msg01875.html

- PR55380 tiny libcpp performance fix + hack for asan/valgrind
  http://gcc.gnu.org/ml/gcc-patches/2012-11/msg01973.html

        Jakub