The normal getopt() function is bloated because it links printf(). This
change exports the original authentic bsd getopt function, that cosmo's
always used internally so cosmocc users don't need to include internals
- Fix handling of precision in hex float formatting
- Enhance the cocmd interpreter for system() and popen()
- Manually ran the Lua unit tests, which are now passing
- Let stdio i/o operations happen when file is in error state
- We're now saving and restoring xmm in ftrace out of paranoia
