Enable build of open62541 against system installed mbedtls library.

coupler/opc-ua-server/Makefile

 CC=$(C_COMPILER)
 CFLAGS= -I $(OPEN62541_SOURCE_HOME) 
-LDFLAGS= -L $(OPEN62541_HOME)/lib
+LDFLAGS= -L $(OPEN62541_HOME)/lib -lmbedcrypto  -lmbedx509
 OUT_DIR= $(BINARY_OUT_DIR)
 
 server: server.c

slapos/software/osie-coupler/software-opc-ua.cfg

@@ -37,6 +37,8 @@ configure-options =
   -DUA_ENABLE_PUBSUB_MONITORING=ON
   -DUA_NAMESPACE_ZERO=FULL
   -DUA_ENABLE_AMALGAMATION=ON
+  -DUA_ENABLE_ENCRYPTION=MBEDTLS
+  -DUA_ENABLE_ENCRYPTION_MBEDTLS=ON
 
 [osie-repository]
 recipe  = slapos.recipe.build:gitclone