[Bug target/91135] [9/10 Regression] __linux__ not defined with -mcall-aixdesc on 9.x and ppc64

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91135

--- Comment #4 from Segher Boessenkool <segher at gcc dot gnu.org> ---
You still haven't said what the kernel uses it for, when, in what way.
It probably shouldn't.  But, -mcall-* should not change whether __linux__
and friends are defined.