Add generic RPC layer

Adds generic RPC caller and endpoint. This is the base for specialized
RPC communication using e.g. FF-A messaging. The protocol description
is implemented in two flavours: packed C structures and protobuf.

Change-Id: I17f450b7272bd4008fc20fe8f716a253f6754000
Signed-off-by: Julian Hall <julian.hall@arm.com>
diff --git a/protocols/rpc/common/packed-c/test/component.cmake b/protocols/rpc/common/packed-c/test/component.cmake
new file mode 100644
index 0000000..28a896b
--- /dev/null
+++ b/protocols/rpc/common/packed-c/test/component.cmake
@@ -0,0 +1,14 @@
+#-------------------------------------------------------------------------------
+# Copyright (c) 2020, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+#-------------------------------------------------------------------------------
+if (NOT DEFINED TGT)
+	message(FATAL_ERROR "mandatory parameter TGT is not defined.")
+endif()
+
+target_sources(${TGT} PRIVATE
+	"${CMAKE_CURRENT_LIST_DIR}/check_rpc_status_packed-c.cpp"
+	)
+