stagefiles: refactor Require_stagefile()

- count of params is available as $#, we don't need the pipe-to-wc logic.
 - the whole 'CONTINUE' based logic is silly, we can just return once one
   of the files is found.
 - setting of 'NAME' in the loop was completely pointless.
 - the error message for multiple files was not very clear just injecting
   a sequence of words into a sentence.
 - it did not work correctly if no arguments were given (bad usage)

note, you might question whether the functionality of this function is
correct, as did I; this is tackled in a followup commit whilst this
commit retains the existing functionality!

Gbp-Dch: Short

functions/stagefile.sh

@@ -63,37 +63,28 @@ Remove_stagefile ()
 	rm -f "${FILE}"
 }
 
+# Find at least one of the required stages, `exit 1` if none found
 Require_stagefile ()
 {
-	local NAME
-	local FILES
-	local NUMBER
-	NAME="$(basename ${0})"
-	FILES="${@}" #must be on separate line to 'local' declaration to avoid error
-	NUMBER="$(echo ${@} | wc -w)"
-
+	if [ $# -eq 0 ]; then
+		Echo_warning "Bad `Require_stagefile` usage, no params were supplied"
+		return 0
+	fi
 	local FILE
-	local CONTINUE=false
-	for FILE in ${FILES}
-	do
-		FILE=".build/${FILE}"
-		# Find at least one of the required stages
-		if [ -f ${FILE} ]
-		then
-			CONTINUE=true
-			NAME="${NAME} $(basename ${FILE})"
+	for FILE in ${@}; do
+		if [ -f ".build/${FILE}" ]; then
+			return 0
 		fi
 	done
 
-	if ! $CONTINUE
-	then
-		if [ "${NUMBER}" -eq 1 ]
-		then
-			Echo_error "%s: %s missing" "${NAME}" "${FILE}"
-		else
-			Echo_error "%s: one of %s is missing" "${NAME}" "${FILES}"
-		fi
+	local NAME
+	NAME="$(basename ${0})"
 
-		exit 1
+	if [ $# -eq 1 ]; then
+		Echo_error "%s requires stage: %s" "${NAME}" "${FILE}"
+	else
+		Echo_error "%s requires one of these stages: %s" "${NAME}" "$(echo ${@})"
 	fi
+
+	exit 1
 }