Add 'zpool status -i' option

Only display the full details of the vdev initialization state
in 'zpool status' output when requested with the -i option.
By default display '(initializing)' after vdevs when they are
being actively initialized.  This is consistent with the
established precident of appending '(resilvering), etc' and
fits within the default 80 column terminal width making it
easy to read.

Additionally, updated the 'zpool initialize' documentation to
make it clear the options are mutually exclusive, but allow
duplicate options like all other zfs/zpool commands.

Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8230

man/man8/zpool.8

@@ -116,7 +116,7 @@
 .Op Ar newpool Oo Fl t Oc
 .Nm
 .Cm initialize
-.Op Fl cs
+.Op Fl c | Fl s
 .Ar pool
 .Op Ar device Ns ...
 .Nm
@@ -187,7 +187,7 @@
 .Nm
 .Cm status
 .Oo Fl c Ar SCRIPT Oc
-.Op Fl DgLpPsvx
+.Op Fl DigLpPsvx
 .Op Fl T Sy u Ns | Ns Sy d
 .Oo Ar pool Oc Ns ...
 .Op Ar interval Op Ar count
@@ -1603,7 +1603,7 @@ Will also set -o cachefile=none when not explicitly specified.
 .It Xo
 .Nm
 .Cm initialize
-.Op Fl cs
+.Op Fl c | Fl s
 .Ar pool
 .Op Ar device Ns ...
 .Xc
@@ -2199,7 +2199,7 @@ and automatically import it.
 .Nm
 .Cm status
 .Op Fl c Op Ar SCRIPT1 Ns Oo , Ns Ar SCRIPT2 Oc Ns ...
-.Op Fl DgLpPsvx
+.Op Fl DigLpPsvx
 .Op Fl T Sy u Ns | Ns Sy d
 .Oo Ar pool Oc Ns ...
 .Op Ar interval Op Ar count
@@ -2226,6 +2226,8 @@ output.  See the
 option of
 .Nm zpool Cm iostat
 for complete details.
+.It Fl i
+Display vdev initialization status.
 .It Fl g
 Display vdev GUIDs instead of the normal device names. These GUIDs
 can be used in place of device names for the zpool