- Move header check from postsubmit to presubmit
- Install third_party/getop if needed
- Modify check-headers test to use system getopt when it's available.
- Moved get_mesa.sh to build/common/get-mesa.sh
- Moved check-headers.sh to test/check-headers/test.sh
- Moved check-metal-shaders.sh to test/check-metal-shaders/test.sh