FindTCL: Fix TCL and TK version variable references (#11528)

FindTCL.cmake switched variables in the FIND_LIBRARY invocation.  The
FIND_LIBRARY() statement for TCL used the TK variables and vice versa.
This patch reverses that into the right usage.

Closes debian issue 600245.

Modules/FindTCL.cmake

@@ -104,7 +104,7 @@ ENDIF(WIN32)
 FIND_LIBRARY(TCL_LIBRARY
   NAMES 
   tcl   
-  tcl${TK_LIBRARY_VERSION} tcl${TCL_TCLSH_VERSION} tcl${TK_WISH_VERSION}
+  tcl${TCL_LIBRARY_VERSION} tcl${TCL_TCLSH_VERSION} tcl${TK_WISH_VERSION}
   tcl86 tcl8.6 
   tcl85 tcl8.5 
   tcl84 tcl8.4 
@@ -117,7 +117,7 @@ FIND_LIBRARY(TCL_LIBRARY
 FIND_LIBRARY(TK_LIBRARY 
   NAMES 
   tk
-  tk${TCL_LIBRARY_VERSION} tk${TCL_TCLSH_VERSION} tk${TK_WISH_VERSION}
+  tk${TK_LIBRARY_VERSION} tk${TCL_TCLSH_VERSION} tk${TK_WISH_VERSION}
   tk86 tk8.6
   tk85 tk8.5 
   tk84 tk8.4