git-gui: Hide the ugly bash command line from the windows desktop icon.

The user really doesn't need to see the technical details of how we
launch git-gui from within their "desktop icon".  Instead we should hide
the command line from being displayed when the icon launches by putting
@ at the start of the line.  If they really need to see the command we
are running they can edit the batch file.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui

@@ -2754,7 +2754,7 @@ proc do_windows_shortcut {} {
 				regsub -all ' $me "'\\''" me
 				regsub -all ' $gd "'\\''" gd
 				puts $fd "@ECHO Starting git-gui... Please wait..."
-				puts -nonewline $fd "\"$sh\" --login -c \""
+				puts -nonewline $fd "@\"$sh\" --login -c \""
 				puts -nonewline $fd "GIT_DIR='$gd'"
 				puts -nonewline $fd " '$me'"
 				puts $fd "&\""