Fix how 1988/applin/zsmall.c is built

To match the rest of the repository with alternate code (where possible)
the file is now applin.alt.c. However the rule in the Makefile copies
the file to zsmall.c and builds it accordingly, compiling into
applin.alt.

.gitignore has had applin.alt added to it.

1988/applin/Makefile

@@ -111,8 +111,8 @@ OBJ= ${PROG}.o
 DATA=
 TARGET= ${PROG}
 #
-ALT_OBJ= zsmall.o
-ALT_TARGET= zsmall
+ALT_OBJ= applin.alt.o
+ALT_TARGET= applin.alt
 
 
 #################
@@ -147,6 +147,10 @@ ${PROG}: ${PROG}.c
 alt: data ${ALT_TARGET}
 	@${TRUE}
 
+${ALT_TARGET}: ${PROG}.alt.c
+	${CP} -f ${PROG}.alt.c zsmall.c
+	${CC} ${CFLAGS} zsmall.c -o $@
+
 # not an official entry
 #
 # The 'zsmall.c' program was obtained from 'applin.c' by reducing its recursion