modify Dockerfile CMD for retry clone

Merge pull request #4 from sinlead/arm-platform

add capable to build image for multiple platforms

divide clone step into clone and fetch unshallow

git clone as shallow

submodule syntax move to final step

Merge pull request #3 from sinlead/update-variable

rename env variable

Add git clone lock

Add git clone lock

Merge pull request #2 from msglight4874/david_init_cache_by_clone

🔧 改用 clone 來 init cache

co co