[gentoo-user] Where is ustat.h?

[Peter Humphrey]

I'm trying to compile gcc-7.3.0-r3 to test a hypothesis, but I get this
failure:

/var/tmp/portage/sys-devel/gcc-7.3.0-r3/work/gcc-7.3.0/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc:157:10: fatal error: sys/ustat.h: No such file or directory
 #include <sys/ustat.h>

I thought it might be in sys-kernel/linux-headers, but installing a
contemporaneous version didn't help. Google doesn't, either.

Can anyone point me in the right direction?

-- 
Regards,
Peter.