rk3399 OTA升级错误问题 make otapackage编译报错 keyerror:out

 make otapackage编译报错 keyerror:out这个问题在各种查找的情况下，终于找到了原因，这里记录一下原因

在make otapackage之前少了一些命令

. build/envsetup.sh && lunch g3399-userdebug（这个可以单独执行lunch命令查看）

然后make otapackage

Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
system: 1923/131072 files (0.0% non-contiguous), 148861/524288 blocks
Traceback (most recent call last):
  File "./build/tools/releasetools/add_img_to_target_files", line 476, in 
    main(sys.argv[1:])
  File "./build/tools/releasetools/add_img_to_target_files", line 470, in main
    AddImagesToTargetFiles(args[0])
  File "./build/tools/releasetools/add_img_to_target_files", line 389, in AddImagesToTargetFiles
    boot_img=boot_image)
  File "./build/tools/releasetools/add_img_to_target_files", line 109, in AddSystem
    block_list=block_list)
  File "./build/tools/releasetools/add_img_to_target_files", line 118, in BuildSystem
    return CreateImage(input_dir, info_dict, "system", block_list=block_list)
  File "./build/tools/releasetools/add_img_to_target_files", line 214, in CreateImage
    img_out = os.path.join(os.environ["OUT"],"system.img")
  File "/usr/lib/python2.7/UserDict.py", line 40, in __getitem__
    raise KeyError(key)
KeyError: 'OUT'
ninja: build stopped: subcommand failed.
build/core/ninja.mk:148: recipe for target 'ninja_wrapper' failed
make: *** [ninja_wrapper] Error 1