- Add `fcntl.h` to `nrhp/opennhrp.c` for `open()`, `O_WRONLY` etc.
 - Add missing `sys/types.h` include to `nrhp/nrhp_common.h` to provide
   required `u_int*_t` types under musl

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>