scripts/codesign_example: Add check for sha256sum program
scripts/codesign_example: Add check for sha256sum program

pecigonzalo/packer,paulmey/packer,rnaveiras/packer,paulmey/packer,paulmey/packer,hashicorp/packer,pecigonzalo/packer,rnaveiras/packer,ricardclau/packer,mitchellh/packer,ricardclau/packer,mitchellh/packer,grubernaut/packer,ricardclau/packer,rnaveiras/packer,paulmey/packer,grubernaut/packer,paulmey/packer,mitchellh/packer,rnaveiras/packer,pecigonzalo/packer,mitchellh/packer,paulmey/packer,hashicorp/packer,hashicorp/packer,grubernaut/packer,mitchellh/packer,grubernaut/packer,ricardclau/packer,grubernaut/packer,hashicorp/packer,rnaveiras/packer,rnaveiras/packer,grubernaut/packer,ricardclau/packer,pecigonzalo/packer,ricardclau/packer