Fix vtkWrapTcl assert on isprint for Visual Studio.

If an out-of-range value is sent to isprint(), then programs generated
by Visual Studio 2010 and later will assert.  I suspect that it does this
because the alternative would be to guess the encoding and potentially
give an incorrect answer, which could compromise the security of the
executable.

Wrapping/Tools/vtkWrapTcl.c

@@ -85,7 +85,9 @@ static const char *quote_string(const char *comment, size_t maxlen)
       strcpy(&result[j],"\\n");
       j += 2;
     }
-    else if (isprint(comment[i]))
+    /* the "0x80" checks for non-ASCII chars, which we do not consider
+       to be printable since we don't know the encoding */
+    else if ((comment[i] & 0x80) == 0 && isprint(comment[i]))
     {
       result[j] = comment[i];
       j++;