[Bug lto/66752] spec2000 255.vortex performance compiled with GCC is ~20% lower than with CLANG

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66752

--- Comment #17 from Jeffrey A. Law <law at redhat dot com> ---
The fix for the ppc64 bootstrap regression looks good.  I'm just having a bear
of a time producing a reasonable test for the regression suite.