Add libstdc++fs to SDK

Change-Id: I9bdbacc7fb763cfcf4c056911152513c7c872299
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/common/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend b/common/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend
index 9b1a15a..ebfb91a 100644
--- a/common/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend
+++ b/common/recipes-core/packagegroups/packagegroup-core-standalone-sdk-target.bbappend
@@ -1 +1 @@
-RRECOMMENDS_${PN}_append = " gtest gmock sdbusplus phosphor-logging"
+RRECOMMENDS_${PN}_append = " gtest gmock sdbusplus phosphor-logging libstdc++-staticdev"