wvstreams: remove tcl dependency support

As far as I can tell enabling tcl support has no affect on the actual
library.  Furthermore, wvstreams has been checking for/linking against
tcl 8.3 which has never been supported in buildroot as far as I can tell
(8.4 added in 2005).  That being said there is clearly no reason to keep
this around.

Signed-off-by: Andrew Ruder <andrew.ruder@elecsyscorp.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>