Fix error message for invalid command line opts

When a command line option is not recognized, the error message across
our build scripts would indirectly dereference OPTIND. This is incorrect
and likely to result in an unbound variable exception.

Replace with printing '-${OPTARG}'.

Change-Id: I191645b876c0bd32a29758d1ac7c31c9a5b7f6b3
3 files changed
tree: 5aafa61b91728a11bffa27414a16863b5d3a0adf
  1. Makefile
  2. aarch64/
  4. kvm-unit-tests/