!11171 custom op env vars setting

From: @zhoufeng54
Reviewed-by: @kisnwang,@chujinjin
Signed-off-by: @chujinjin

mindspore/_check_version.py

@@ -232,7 +232,14 @@ class AscendEnvChecker(EnvChecker):
         self.check_deps_version()
 
         if Path(self.op_impl_path).is_dir():
+            # python path for sub process
+            if os.getenv('PYTHONPATH'):
+                os.environ['PYTHONPATH'] = self.op_impl_path + ":" + os.environ['PYTHONPATH']
+            else:
+                os.environ['PYTHONPATH'] = self.op_impl_path
+            # sys path for this process
             sys.path.append(self.op_impl_path)
+
             os.environ['TBE_IMPL_PATH'] = self.op_impl_path
         else:
             raise EnvironmentError(