Fix libQtCore link failure because of missing libz

libQtCore often, but not always includes the required functionality from
libz. This is needed for example on openSUSE 12.1 and 12.2.

ApplicationCode/CMakeLists.txt

@@ -234,6 +234,7 @@ if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
         ${CMAKE_CURRENT_SOURCE_DIR}/../ThirdParty/Ert/geometry/lib/libgeometry.a
         ${CMAKE_CURRENT_SOURCE_DIR}/../ThirdParty/Ert/well/lib/libwell.a
         lapack
+	z # In case libz is not included in libQtCore
     )
 elseif(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
     set ( EXTERNAL_LINK_LIBRARIES