Predefined preprocessor #defines

Note: additional predefines may be added from the command line using the -D
flag.  Also, anything defined in either options.h will be available surrounded
by __; e.g if FOO is defined in options.h, the __FOO__ will be defined in all
objects.

The following identifiers may be defined:

<DL>
* MUDOS: always defined
* "2.7.2": a string representing the version of MudOS being run
* __PORT__: archaic; the port number of the first (previously, the only) external port
* __ARCH__: the name of the architecture of the machine
* __COMPILER__: the compiler MudOS was compiled with
* __OPTIMIZATION__: the optimization used
* MUD_NAME: the MUD name from the config file
* HAS_ED: defined if the ed() efun is available
* HAS_PRINTF: defined if the printf() efun is available
* HAS_RUSAGE: defined if the rusage() efun is available
* HAS_DEBUG_LEVEL: defined if the debug_level() efun is available
* "doc/concepts/defines.c": the file being compiled
* __DIR__: the directory the file is in (with the trailing /)
</DL>

 Tim Hollebeek  Beek@ZorkMUD, Lima Bean, IdeaExchange, and elsewhere
