Add dev packages to openbmc yocto sdk

In the current state, the master sdk does not contain the
following packages, hence it is currently broken.
 - nlohmann-json
 - function2
 - cli11
 - libcereal

Most of the the OpenBMC repositories depend on the above mentioned
packages and does not build in their absence. This commit would
attempt to fix that.

Tested with a newly created SDK with this change and observed that
the header files of above packages are placed in the sdk.

Change-Id: I3b8dde8f5242279f856f3d3ecd3b78a1e93f6ffd
Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.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 f8d6292..0eab6b3 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
@@ -1,6 +1,10 @@
 RRECOMMENDS:${PN}:append = " \
+    cli11-dev \
+    function2-dev \
     googletest \
+    libcereal-dev \
     libstdc++-staticdev \
+    nlohmann-json-dev \
     phosphor-dbus-interfaces-yaml \
     phosphor-logging \
     sdbusplus \