[Bug target/69734] no_caller_saved_registers attribute doesn't work with -mavx512f -g

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69734

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
This is on hjl/interrupt/stage1 branch.  Trunk never spills mask
registers.