Update jgit-describe.jar: "Filter properly on Windows."

Change-Id: I1bf4b2f43ecde3faed72a8034d2f83e04f00f01d
Reviewed-on: http://gerrit.dmdirc.com/2345
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Reviewed-by: Chris Smith <chris@dmdirc.com>
Automatic-Compile: DMDirc Build Manager