Add fastboot --os-version and --os-patch-level.

Also move -c to --cmdline to match the python mkbootimg tool. Remove
the short options for these rarely-used options.

Remove #if 0 cruft from <bootimg/bootimg.h>.

Bug: http://b/77340848
Test: manual testing (need to fix http://b/77809061 for unit tests)
Change-Id: Ieaa795566611bd89ba3fee39a1d9f6ad0713a587