[RFC] remove gettimeofday() usage

Ping @equalsraf. When this is merged, you'll probably be able to excise a hack.
I've removed the `defined(HAVE_GETTIMEOFDAY) && defined(HAVE_SYS_TIME_H)`, so now it will be activated on all UNIX platforms. That still doesn't jive well with me, as `:help` says win32 has it too. But maybe the option was used in some win32 specific GUI code as well...