fix(rt-thread): fix compiler cannot find the lvgl/lvgl.h file with SquareLine (#3814)

env_support/rt-thread/squareline/SConscript

@@ -1,13 +1,10 @@
 from building import *
 
 cwd = GetCurrentDir()
-group = []
+src = ['lv_ui_entry.c']
-src = []
-CPPPATH =[]
 
 src += Glob(cwd + '/ui/*.c')
-CPPPATH += [cwd+'/ui']
 
-group = group + DefineGroup('LVGL-SquareLine', src, depend = ['PKG_USING_LVGL_SQUARELINE'], CPPPATH = CPPPATH)
+group = DefineGroup('LVGL-SquareLine', src, depend = ['PKG_USING_LVGL_SQUARELINE'])
 
 Return('group')

env_support/rt-thread/squareline/lv_ui_entry.c

@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2006-2022, RT-Thread Development Team
  *
- * SPDX-License-Identifier: Apache-2.0
+ * SPDX-License-Identifier: MIT
  *
  * Change Logs:
  * Date           Author        Notes

env_support/rt-thread/squareline/ui/lvgl/lvgl.h

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2022-11-20     Meco Man     The first version
+ */
+
+#ifdef __RTTHREAD__
+
+#include "../../../../../lvgl.h" /* back to the root folder's lvgl.h */
+
+#endif /* __RTTHREAD__ */