netutils/dropbear: retain child exit status for NSH PTY session

The per-session NSH task is reaped with waitpid() in
dropbear_nshsession.c.  Without CONFIG_SCHED_CHILD_STATUS the kernel does
not retain the child exit status, so waitpid() returns ECHILD right after
authentication and the interactive session never starts
("NSH session wait failed: Unknown error 10").

Depend on SCHED_HAVE_PARENT and SCHED_CHILD_STATUS (following the project's
depends-on-over-select convention) so the requirement is explicit; boards
enabling Dropbear must set these in their defconfig.

Signed-off-by: Felipe Moura <moura.fmo@gmail.com>

Author: FelipeMdeO

netutils/dropbear/Kconfig

@@ -10,6 +10,8 @@ menuconfig NETUTILS_DROPBEAR
 	depends on !DISABLE_PSEUDOFS_OPERATIONS
 	depends on !DISABLE_PTHREAD
 	depends on SCHED_WAITPID
+	depends on SCHED_HAVE_PARENT
+	depends on SCHED_CHILD_STATUS
 	depends on NSH_LIBRARY
 	depends on FSUTILS_PASSWD
 	depends on PSEUDOTERM