Merge pull request #793 from ifilippov/master

Support LLVM trunk (build and errors)
Merge pull request #794 from ifilippov/master

Deleting print from 'safe_for_all_mask_off' functions
Add error messages for structs containing nested undefined structs
Merge pull request #795 from jbrodman/undefinedmemberstructs

Add error messages for structs containing nested undefined structs
support LLVM