perf: v5.3+ build fixes

perf: v5.3+ build fixes

In the 5.3+ perf builds, there are multiple unistd.h files that need
to be kept in sync. So not only do we update one, we update both to
ensure that libc-headers and the perf build are in sync.

perf checks some key files itself to be sure they are in sync, and
bits.h can be out of sync. There's no build error that results with
bits.h at the moment, but we still make sure they are in sync to
avoid the configure/compile warning.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>