!13704 [MS][LITE][r1.2] it doesn't clear the output/ when build inference package

From: @sunsuodong
Reviewed-by: @zhang_xue_tong,@zhanghaibo5
Signed-off-by: @zhang_xue_tong

build.sh

@@ -538,6 +538,7 @@ write_commit_file() {
 
 build_lite()
 {
+    rm -rf ${BASEPATH}/output/*
     get_version
     echo "============ Start building MindSpore Lite ${VERSION_STR} ============"
     local LOCAL_LITE_PLATFORM=${LITE_PLATFORM}