[svn-r30113] Description:

Clean up warnings (from 2774 -> 1560, with my standard debug build)

Tested on:
    MacOSX/64 10.11.5 (amazon) w/serial, parallel & production
    (h5committest forthcoming)

tools/h5diff/h5diff_common.c

@@ -358,7 +358,7 @@ void parse_command_line(int argc,
  *
  *-------------------------------------------------------------------------
  */
-static int
+H5_ATTR_PURE static int
 check_n_input( const char *str )
 {
     unsigned i;