Use usual location as open62541 copies generated by amalgation switch...

Use usual location as open62541 copies generated by amalgation switch generated files to its source folder and libraries in its build folder.

coupler/opc-ua-server/Makefile

 CC=arm-linux-gnueabihf-gcc
-CFLAGS= -I $(OPEN62541_HOME)/build 
-LDFLAGS= -L $(OPEN62541_HOME)/build/bin
+CFLAGS= -I $(OPEN62541_SOURCE_HOME) 
+LDFLAGS= -L $(OPEN62541_HOME)/lib
 OUT_DIR=bin/
 
 server: server.c
-	$(CC) -o $@ $^ $(CFLAGS) $(LDFLAGS) -std=c99 $(OPEN62541_HOME)/build/open62541.c
+	$(CC) -o $@ $^ $(CFLAGS) $(LDFLAGS) -std=c99 $(OPEN62541_SOURCE_HOME)/open62541.c
 	@cp server $(OUT_DIR)
 	@rm server