If TCL cannot be found, disable it for the remainder of configure to avoid fatal errors with version check

build/autotools/includes/libtcl.m4

@@ -408,6 +408,7 @@ configure: error:
   --with-tclinc='/path/to/tcl.h' options.
 
 EOF
+    enable_script_tcl="no"
     else
       AC_DEFINE(HAVE_LIBTCL, 1, [Define if you have support for libtcl])
     fi

configure

@@ -5928,6 +5928,7 @@ configure: error:
   --with-tclinc='/path/to/tcl.h' options.
 
 EOF
+    enable_script_tcl="no"
     else
 
 $as_echo "#define HAVE_LIBTCL 1" >>build/confdefs.h