com.jcraft.jsch requires com.jcraft.jzlib to provide optional zlib
packet compression support. Add this library so that jgit can handle
packet compression.
CQ: 15292
Bug: 529129
Change-Id: I0297bd0488753547a5f5d47dbf0db508a79dd265
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>