Elvis uses many preprocessor symbols to control compilation...

-DM_SYSV
	If defined, then Elvis uses SysV ioctl() calls to control the tty;
	normally it uses V7/BSD/Minix ioctl() calls.

	The M_SYSV symbol is a "manifest" symbol on all SysV compilers I've
	ever used.  This means it is defined by default on a SysV system, so
	you probably don't need to define it explicitly.  Because of this,
	the BSD nakefile will work WITHOUT MODIFICATION on many SysV systems.
	I know it works for SCO Xenix.

	SysV users should first try the BSD makefile as-is; if that doesn't
	work, then add "-DM_SYSV" to the CFLAGS line in the Makefile.

-DDATE=\'\"`date`\"\'
	DATE should be defined to be a string constant.  It is printed by the
	:version command as the compilation date of the program.

	It is only used in cmd1.c, and even there you may leave it undefined
	without causing an urp.

	The form shown above only works if you use "eval".  See the Makefile.

-DTMPNAME=\"/tmp/vi%04x%04x\"
	This allows you to use a different name for Elvis' temporary files.
	The default value is defined near the top of vi.h, so you only need
	to use this on the commandline if the default name is wrong.

	It should contain two "%d" or "%x" formats, which are replaced by
	the inode number and device major/minor number.

-DCUTNAME=\"/tmp/cut%04x%04x\"
	This is similar to TMPNAME, but is used to generate names for old
	temp files which are being kept around because they are refered to
	by cut buffers.

	It should contain two "%d" or "%x" formats, which are replaced by the
	Elvis' getpid() and file-descriptor numbers.

-DCRUNCH
	This option causes some large & often-used macros to be replaced by
	equivelent functions.  It reduces the size of the ".text" segment by
	about 4K, and you don't sacrifice any features -- just a little speed.

-DSET_NOCHARATTR
	Permanently disables the charattr option.  This reduces the size of
	your ".text" segment by about 850 bytes.

-DNO_RECYCLE
	Normally, Elvis will recycle space from the tmp file which contains
	totally obsolete text.  This flag disables this recycling.  Without
	recycling, the ".text" segment is about 1K smaller that it would
	otherwise be, but the tmp file grows much faster.  If you have a lot
	of free space on your harddisk, but Elvis is too bulky to run with
	recycling, then try it without recycling.

-DDEBUG
	This adds the ":debug" and ":validate" commands, and also adds many
	internal consistency checks.  It increases the size of the ".text"
	segment by about 5K.
