t (see environ.h and utils1.c)

   Leptonica provides both compile-time and run-time control over
   messages and debug output (thanks to Dave Bryan).  Both compile-time
   and run-time severity thresholds can be set.  The runtime threshold
   can also be set by an environmental variable.  Messages are
   vararg-formatted and of 3 types: error, warning, informational.
   These are all macros, and can be further suppressed when
   NO_CONSOLE_IO is defined on the compile line.  For production code
   where no