Revert "Correct wnck/gtk3 check."

This reverts commit a2b1af54a24b93766f5e2ed4a216637dc510ec47.
Revert "Fixed the WNCK_CHECK_VERSION calls to only be used when GTK is version"

This reverts commit 428e32cd0f3f2df0cbd4e859304f0935a11612bc.
Check if WNCK_CHECK_VERSION is defined
Merge pull request #145 from infirit/master

Check if WNCK_CHECK_VERSION is defined