Improved source code flow

Changed /*NOTREACHED*/ to not_reached(); and use "attribute.h".

Added .PHONY rule, just after all rule, to Makefiles.

Fixed an improper indentation issue.

cscript/Makefile

@@ -1,7 +1,7 @@
 #
 # cscript - makefile for calc shell script files
 #
-# Copyright (C) 1999-2006,2014,2017,2021  Landon Curt Noll
+# Copyright (C) 1999-2006,2014,2017,2021,2022  Landon Curt Noll
 #
 # SRC: cscript/Makefile
 #
@@ -297,11 +297,17 @@ CALCLIBLIST=
 #
 CSCRIPT_TARGETS= ${SCRIPT}
 TARGETS= ${CSCRIPT_TARGETS} README
+#
+# rules that are not also names of files
+#
+PHONY= all clobber distlist install
 
 # The reason for this Makefile
 #
 all: ${TARGETS} .all
 
+.PHONY: ${PHONY}
+
 README: README.src
 	@${RM} -f $@
 	@${SED} -e "s:#!/usr/local/src/bin/calc/calc:#!${BINDIR}/calc:" $?>$@