etcd-cpp-apiv3: enabled sdk build

Change-Id: I7e6541849e03b5041a86f2e22532de4c15c8ac78
Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
diff --git a/meta-phosphor/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend b/meta-phosphor/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend
index 0eab6b3..a9bf7c8 100644
--- a/meta-phosphor/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend
+++ b/meta-phosphor/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend
@@ -9,3 +9,4 @@
     phosphor-logging \
     sdbusplus \
     "
+RRECOMMENDS:${PN}:append:df-etcd = " etc-cpp-apiv3 protobuf"