POSIX obsoleted the getitimer/setitimer API a decade ago, and now's a good time 
for Emacs to stop using this obsolescent API, partly to simplify other timestamp 
improvements that I have in mind, partly to head off any other lurking bugs like 
the problem I just fixed in commit 238c7cd730819ddba2dbde3c46ee36136575695b 
relating to a mistaken assumption about the old API.

Attached please find two proposed patches. The first simplifies Emacs proper to 
just use the current timer_gettime/timer_settime API instead (this is the 
standard replacement for the obsolescent API). The second patch affects only the 
MS-Windows code, modifying it to use the new API instead of the old one; I 
haven't tested it as I don't use MS-Windows.