[Bug libstdc++/90440] [8/9/10 regression] Solaris/SPARC 10 fails to find <ext/opt_random.h>

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90440

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The libstdc++ config should select one of these headers to use:

./config/cpu/i486/opt/ext/opt_random.h
./config/cpu/aarch64/opt/ext/opt_random.h
./config/cpu/generic/opt/ext/opt_random.h

There should be an "ext" dir containing a symlink to the chosen file, which
will be found by
-I/export/home/jullien/gcc-8.3.0/obj/sparc-sun-solaris2.10/libstdc++-v3/include/sparc-sun-solaris2.10

It's possible that for --enable-obsolete this isn't set up correctly (although
I think solaris2.10 is only obsolete for gcc-9 not gcc-8).