Unify the time handling

Some options are in seconds, if no units are given. These include
runtime/timeout, startdelay, and ramp_time. Handle this
appropriately. Internally it should all be microseconds now, it's
just the conversion factor.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fio.1 b/fio.1
index 81b03f7..c530d84 100644
--- a/fio.1
+++ b/fio.1
@@ -131,8 +131,8 @@
 values. Specifying '30GiB' will get you 30*1000^3 bytes.
 When specifying times the default suffix meaning changes, still denoting the
 base unit of the value, but accepted suffixes are 'D' (days), 'H' (hours), 'M'
-(minutes), 'S' Seconds, 'ms' milli seconds. Time values without a unit specify
-seconds.
+(minutes), 'S' Seconds, 'ms' (or msec) milli seconds, 'us' (or 'usec') micro
+seconds. Time values without a unit specify seconds.
 The suffixes are not case sensitive.
 .TP
 .I bool