time magic: shorten unnecessary output on windows

On windows the detailed info (i.e. cpu time) is not available and
always reported as zero. The rest of the information is therefore
redundant with the next print (wall time) and can be omitted.
Merge pull request #2961 from JanSchulz/shorter_time_magic

%time magic: shorten unnecessary output on windows

On windows the detailed info (i.e. cpu time) is not available and
always reported as zero. The rest of the information is therefore
redundant with the next print (wall time) and can be omitted.