Add 1998/schweikh3 alt code

This is for the rare case that the author described where the size needs
to be increased: it can now be done when compiling without having to
update the code. The original code is the recommended one try first; if
any of '-D' macros are not defined it will use the default, including
the size one. This so to make it easier to redefine just one, rather
than having to specify all the -D options.

1998/schweikh3/Makefile

@@ -113,8 +113,8 @@ OBJ= ${PROG}.o
 DATA= samefile.1
 TARGET= ${PROG}
 #
-ALT_OBJ=
-ALT_TARGET=
+ALT_OBJ= ${PROG}.alt.o
+ALT_TARGET= ${PROG}.alt
 
 
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