status: color in-progress message like other header messages

The "status" command recently learned to describe the
in-progress operation in its long output format (e.g.,
rebasing, am, etc). This message gets its own slot in the
color table, even though it is not configurable. As a
result, if the user has set color.status.header to a
non-default value, this message will not match (and cannot
be made to match, as there is no config option).

It is probably more sane to just color it like the rest of
the text (i.e., just use color.status.header). This would
not allow users to customize the color of this message
independently, but they cannot do that with the current code
anyway, and if somebody wants to build customizable
colorization later, this patch does not make it much harder
to do so.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

wt-status.h

@@ -15,7 +15,6 @@ enum color_wt_status {
 	WT_STATUS_LOCAL_BRANCH,
 	WT_STATUS_REMOTE_BRANCH,
 	WT_STATUS_ONBRANCH,
-	WT_STATUS_IN_PROGRESS,
 	WT_STATUS_MAXSLOT
 };