[svn-r13434] Used const char * instead of char pointer for HDremove_all function that is used

on VMS. This should fix C++ compilation failures on VMS.

Platforms tested:
	kagiso, VMS is stilll going on.

src/H5system.c

@@ -559,7 +559,7 @@ void HDsrand(unsigned int seed)
  */
 #ifdef H5_VMS
 int
-HDremove_all(char *fname)
+HDremove_all(const char *fname)
 {
     int ret_value = -1;
     char *_fname;