I get a not supported by windows message in the console after the desired timeout. CTRL-c stops it just fine, and the results are also displayed nicely.
The console output:
C:\dev\go\bin> ./gobench -u http://localhost/ -c 1500 -t 15
Dispatching 1500 clients
Waiting for results...
2016/05/26 15:47:42 not supported by windows
go version go1.6.2 windows/amd64