std.time.Timer.lap: only read system time once (#4533)
std.time.Timer.lap: only read system time once (#4533)

Calling Timer.lap queried the system time twice; once to compute the lap
time and once to reset the timer. This can lead to time discrepancies
between actual and computed durations when summing the result of
Timer.lap in a loop. This commit fixes that.

also fix Timer.read to not require a pointer
raulgrell/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig