[PATCH] DW_TAG_typedef and DW_TAG_structure_type not emitted when typedef is used

[jyoti allur]

  Thanks for your quick feedback.
  I will modify the comment & grep as suggested and also check if it can be moved to CodeGenXX files.
  Could you please clarify what you mean by ' non-typedefs used in this context ?'

http://llvm-reviews.chandlerc.com/D2498