[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #4 from vries at gcc dot gnu.org ---
ping^2:
- https://gcc.gnu.org/ml/gcc-patches/2015-04/msg00796.html
- https://gcc.gnu.org/ml/gcc-patches/2015-04/msg00797.html