- Add FindTCL.cmake to fix FreeBSD detection

- Only call Tcl_CreateNamespace when available in the public API,
  fix compatibility with older release

src/plugins/scripts/tcl/CMakeLists.txt

@@ -20,9 +20,14 @@ weechat-tcl-api.c weechat-tcl-api.h)
 SET_TARGET_PROPERTIES(tcl PROPERTIES PREFIX "")
 
 IF(TCL_FOUND)
+  SET(CMAKE_REQUIRED_INCLUDES "${TCL_INCLUDE_PATH}")
+  SET(CMAKE_REQUIRED_LIBRARIES "${TCL_LIBRARY}")
+  CHECK_SYMBOL_EXISTS(Tcl_CreateNamespace tcl.h HAVE_TCL_CREATE_NS)
+
   INCLUDE_DIRECTORIES(${TCL_INCLUDE_PATH})
   SET(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${TCL_LFLAGS}")
   TARGET_LINK_LIBRARIES(tcl ${TCL_LIBRARY} weechat_scripts)
+
 ENDIF(TCL_FOUND)
 
 INSTALL(TARGETS tcl LIBRARY DESTINATION lib/weechat/plugins)

src/plugins/scripts/tcl/weechat-tcl-api.c

@@ -4896,8 +4896,10 @@ void weechat_tcl_api_init (Tcl_Interp *interp) {
     /* standard initializer */ 
     Tcl_Init (interp);
     
+#ifdef HAVE_TCL_CREATE_NS
     /* create weechat namespace */
     Tcl_CreateNamespace (interp, "weechat",(ClientData)0,NULL);
+#endif
 
     /* interface constants */
     /* set variables, TODO: make them unmodifiable (thru Tcl_TraceVar) ? */