sys-auth/sssd: Add sys-apps/shadow to DEPEND (and not RDEPEND)

It is not linked, but it is needed for the shadow/subid.h header. The package is
in the @system set, but we should still explicitly depend on it when headers are
needed.

Signed-off-by: James Le Cuirot <chewi@gentoo.org>

sys-auth/sssd/sssd-2.10.1.ebuild

@@ -77,6 +77,8 @@ RDEPEND="${DEPEND}
 	acct-group/sssd
 	passkey? ( sys-apps/pcsc-lite[policykit] )
 	selinux? ( >=sec-policy/selinux-sssd-2.20120725-r9 )"
+DEPEND+="
+	sys-apps/shadow"
 BDEPEND="
 	acct-user/sssd
 	acct-group/sssd

sys-auth/sssd/sssd-2.9.6-r1.ebuild

@@ -75,6 +75,8 @@ DEPEND="
 RDEPEND="${DEPEND}
 	passkey? ( sys-apps/pcsc-lite[policykit] )
 	selinux? ( >=sec-policy/selinux-sssd-2.20120725-r9 )"
+DEPEND+="
+	sys-apps/shadow"
 BDEPEND="
 	virtual/pkgconfig
 	app-text/docbook-xml-dtd:4.4