Fixes setting of module path for installed package.

Previously the module path was a relative to the install
directory. Because of this dependant modules did not find
the macros of dune-common and cmake configure did not succeed.
With this the CMake package configuration file contains the
full path and the macros are found (even if there is no local
dune-common lying around).

cmake/pkg/dune-common-config.cmake.in

@@ -20,5 +20,5 @@ set(@DUNE_MOD_NAME@_SCRIPT_SOURCE_DIR "${_prefix}/share/cmake/scripts")
 set(DOXYSTYLE_FILE "${_prefix}/share/doc/dune-common/doxygen/Doxystyle")
 set(@DUNE_MOD_NAME@_DEPENDS "@DUNE_DEPENDS@")
 set(@DUNE_MOD_NAME@_SUGGESTS "@DUNE_SUGGESTS@")
-set(@DUNE_MOD_NAME@_MODULE_PATH "@DUNE_INSTALL_MODULEDIR@")
-endif(NOT @DUNE_MOD_NAME@_FOUND)
\ No newline at end of file
+set(@DUNE_MOD_NAME@_MODULE_PATH "${_prefix}/@DUNE_INSTALL_MODULEDIR@")
+endif(NOT @DUNE_MOD_NAME@_FOUND)