Allow --force flag with --grow

.. so that you can 'grow' a raid1 to only one device.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>

ChangeLog

@@ -19,6 +19,7 @@ Changes Prior to this release
 	unless -v is given (-vv gives the old behaviour with -Dsv).
 	This is because the device list can change and so is not a
 	stable aspect of the array
+    -   Allow --force with --grow so '-Gfn1' works (on raid1)
 	
 Changes Prior to 1.11.0 release
     -   Fix embarassing bug which causes --add to always fail.

mdadm.c

@@ -493,6 +493,7 @@ int main(int argc, char *argv[])
 			continue;
 
 		case O(BUILD,'f'): /* force honouring '-n 1' */
+		case O(GROW,'f'): /* ditto */
 		case O(CREATE,'f'): /* force honouring of device list */
 		case O(ASSEMBLE,'f'): /* force assembly */
 		case O(MISC,'f'): /* force zero */