*.mk configuration files modified for compatibility with latest version

of Mentor Sourcery CodeBench Lite toolchain
(https://sourcery.mentor.com/GNUToolchain/release2641).
All detected issues fixed.

src/cmd/basic/basic.c

@@ -1534,7 +1534,7 @@ int get_value()
         value = get_num();
     else {
         ++cmdptr;
-        switch (c) {
+        switch ((int)c) {
         case '(':                       /* nesting */
             value = eval_sub();
             break;