修复ci编译报错

Author: Rbb666

rt-thread/tools/building.py

@@ -824,8 +824,8 @@ def local_group(group, objects):
             CFLAGS = Env.get('CFLAGS', '') + group.get('LOCAL_CFLAGS', '')
             CCFLAGS = Env.get('CCFLAGS', '') + group.get('LOCAL_CCFLAGS', '')
             CXXFLAGS = Env.get('CXXFLAGS', '') + group.get('LOCAL_CXXFLAGS', '')
-            CPPPATH = Env.get('CPPPATH', ['']) + group.get('LOCAL_CPPPATH', [''])
-            CPPDEFINES = Env.get('CPPDEFINES', ['']) + group.get('LOCAL_CPPDEFINES', [''])
+            CPPPATH = list(Env.get('CPPPATH', [''])) + group.get('LOCAL_CPPPATH', [''])
+            CPPDEFINES = list(Env.get('CPPDEFINES', [''])) + group.get('LOCAL_CPPDEFINES', [''])
             ASFLAGS = Env.get('ASFLAGS', '') + group.get('LOCAL_ASFLAGS', '')
 
             for source in group['src']: