Make (char*, size_t) typemap usable for strings of other types in Java.

Notably it now works for "unsigned char*" strings.

Add a test to check that it now works in Java and also showing that it already
worked for the other languages with support for this typemap.

Examples/test-suite/java/char_binary_runme.java

@@ -20,5 +20,11 @@ public class char_binary_runme {
 
     if (t.strlen(hil0) != 4)
       throw new RuntimeException("bad multi-arg typemap");
+
+    if (t.ustrlen(hile) != 4)
+      throw new RuntimeException("bad multi-arg typemap");
+
+    if (t.ustrlen(hil0) != 4)
+      throw new RuntimeException("bad multi-arg typemap");
   }
 }