Merge pull request #2160 from RT-Thread/fix_BSPPath

[tools] Add BSP path into Kernel Group.

tools/building.py

@@ -286,8 +286,8 @@ def PrepareBuilding(env, root_directory, has_libcpu=False, remove_components = [
 
     # add program path
     env.PrependENVPath('PATH', rtconfig.EXEC_PATH)
-    # add rtconfig.h path
-    env.Append(CPPPATH = [str(Dir('#').abspath)])
+    # add rtconfig.h/BSP path into Kernel group
+    DefineGroup("Kernel", [], [], CPPPATH=[str(Dir('#').abspath)])
 
     # add library build action
     act = SCons.Action.Action(BuildLibInstallAction, 'Install compiled library... $TARGET')