[OE-core] useradd: Add missing DEPEND on shadow

[Richard Purdie]

Without this rootfs generation fails as an RDEPENDS is added
but the package might not have bneen built.

Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
diff --git a/meta/classes/useradd.bbclass b/meta/classes/useradd.bbclass
index 8cd7f4f..7faf1a7 100644
--- a/meta/classes/useradd.bbclass
+++ b/meta/classes/useradd.bbclass
@@ -2,7 +2,7 @@
 # target sysroot, and shadow -native and -sysroot provide the utilities
 # and support files needed to add and modify user and group accounts
 DEPENDS_append = "${USERADDDEPENDS}"
-USERADDDEPENDS = " base-passwd shadow-native shadow-sysroot"
+USERADDDEPENDS = " base-passwd shadow-native shadow-sysroot shadow"
 USERADDDEPENDS_virtclass-nativesdk = ""
 
 # This preinstall function will be run in two contexts: once for the