Some small changes to simplify the generated IR.
+ mark the alloc routines as no alias (=attribute(malloc)).
  This marks every alloc call as noalias in the IR.
  (While I felt somewhat frightened by the malloc attribute AFAIK the generated IR looks reasonable.)
+ inline the trivial Box constructor
+ fix dead allocs pass: we will now remove the useless list creation inside f2 in speculation_test.py
Merge pull request #184 from undingen/simplify_ir

Some small changes to simplify the generated IR.