commontk/CTK — pull request #345 by jcfr (2013-06-22 00:17:03+00:00)
Title: Fix CMake unused variable warnings

Introduced by commit 8c9868f5, the variables "ExternalProjectsContrib_DIR"
and "PluginsContrib_DIR" where unconditionally passed down when
configuring CTK inner project.

This commit avoid the "unused variable" warnings by checking the value
of "CTK_USE_CONTRIBUTED_PLUGINS" variable before passing the variables.