nss's build system assumes that cdefs.h is always available on linux
which is not the case with musl
(From OE-Core rev: c4a5a8c4a6dbdcf735024aaee9e36a7a7b56cb96)
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>