git-gui: handle really long error messages in updateindex.
git-gui: handle really long error messages in updateindex.

As reported to msysGit (bug #340) it is possible to get some very
long error messages when updating the index. The use of a label to
display this prevents scrolling the output. This patch replaces the
label with a scrollable text widget configured to look like a label.

Signed-off-by: Pat Thoyts <fe43a83262eef1680511f524a1e74d43c633cffe@users.sourceforge.net>
Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git