lobal parameter, LeptDebugOK, initialized to 0.
   It can be overridden either at compile time by changing the initialization
   (in writefile.c), or at runtime, using setLeptDebugOK().
   The programs in the prog directory, which mostly test functions in
   the library, are not subject to this restriction.

3. GNU runtime functions for stream redirection to memory

   There are two non-standard gnu functions, fmemopen() and open_memstream(),
   that only work on Linux and conveniently allow memory I/O with