NOTES ON BUILDING CURVES
------------------------

- #undef umode_t

  Unfortunately, I don't recall where I needed to access umode_t and
  it wasn't available.  The autoconf test is simplistic in that it
  will only #define the missing type.  This causes problems on the 64
  bit platform IA64 because umode_t isn't found in one of the places
  that the autoconf test checks *but* it is found elsewhere.
  <signal.h> includes a file that defines it and WHAMMO the typedef
  fails.  So, we #undef it before including signal.h.
