[Bug target/82941] Missing vzeroupper with -march=skylake-avx512 -O2

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82941
Bug 82941 depends on bug 82942, which changed state.

Bug 82942 Summary: Generate vzeroupper with -mavx512f -mno-avx512er -O2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82942

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED