[Bug target/79793] Incorrect stack alignment for interrupt handler in 64-bit

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79793

--- Comment #10 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 41827
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41827&action=edit
An untested patch