[Bug pch/68176] [4.9/5/6 Regression] all pch tests fail on eglibc systems (with bits/predefs.h)

[nix at esperi dot org.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68176

--- Comment #5 from Nix <nix at esperi dot org.uk> ---
I didn't think of that (I try to forget that fixincludes exists because it
gives me nightmares). But much though I hate fixincludes, this sort of fix (to
headers for an obsolete program which will by definition never be fixed) is
more or less exactly what it was designed for, and seems a perfect fit for this
case. The question is whether further adjustments are needed to compensate for
the removal of <bits/predefs.h>... I'll do some experimentation.