Comment # 4 on bug 1133245 from Dr. Werner Fink

The problem seems to be that <bits/sigcontect.h> is a copy of
<asm/sigcontext.h> but with stripped comments.  Interesting that this cause
trouble if -flto is used as the definitions are equal and the compiler should
not throw an error but only a warning.  AFAICR <bits/sigcontect.h> is read by
<signal.h> for -D_DEFAULT_SOURCE (which enables __USE_MISC)

Beside this I've added your change of submit request 697610 by hand but have to
decline it because I was not aware of this request, sorry!