[Bug debug/60152] [4.9 Regression] multiple AT_calling_convention attributes generated after r205679

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60152

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> ---
See PR 60060 comment 7 for some details and a backtrace of the two
add_calling_convention_attribute calls.