Fixed live/Makefile (#1182)

## Problem

- The tarballs are not updated after touching any source file:
``` console
> touch root/tmp/README.md
> make
make: Nothing to be done for 'all'.
```

## Solution

- Add dependencies to all source files
- Additionally the process is less verbose now

## Testing

- Tested manually

```console
> touch root/tmp/README.md
> make
dist/root.tar.xz updated
```

live/Makefile

@@ -25,19 +25,31 @@ $(DESTDIR):
 
 # copy the files from src/ to dist/
 $(DESTDIR)/%: $(SRCDIR)/%
-	cp -f $< $@
+	@if [ -e "$@" ]; then MSG="updated"; else MSG="created"; fi; \
+	cp -f $< $@ ;\
+	echo "$@ $${MSG}"
 
 # make a tarball from a directory
 # the tarball is reproducible, i.e. the same sources should result in the very
 # same tarball (bitwise) for the file time stamps use the date of the last
 # commit in the respective directory, use the UTC date to avoid possible time
 # zone and DST differences
-$(DESTDIR)/%.tar.xz: %
+#
+# we need the second expansion here to depend on all files in the source
+# directory, the first expansion expands `%` and reduces the escaped $$
+# to a single $, the second expansion runs $(shell find ...)
+# https://www.gnu.org/software/make/manual/html_node/Secondary-Expansion.html
+.SECONDEXPANSION:
+$(DESTDIR)/%.tar.xz: % $$(shell find % -type f,l)
+	@if [ -e "$@" ]; then MSG="updated"; else MSG="created"; fi; \
 	MTIME=$$(date --date="$$(git log -n 1 --pretty=format:%ci $<)" --utc +"%Y-%m-%d %H:%M:%S"); \
-	(cd $< && find . -xtype f -not -name README.md | LC_ALL=C sort | tar -c -v -f - --format=gnu --owner=0 --group=0 --files-from - --mtime="$$MTIME") | xz -c -9 -e > $@
+	(cd $< && find . -type f,l -not -name README.md | LC_ALL=C sort | tar -c -f - --format=gnu --owner=0 --group=0 --files-from - --mtime="$$MTIME") | xz -c -9 -e > $@; \
+	echo "$@ $${MSG}"
 
 # build the ISO locally
 build: $(DESTDIR)
 	if [ ! -e  $(DESTDIR)/.osc ]; then make clean; osc co -o $(DESTDIR) systemsmanagement:Agama:Staging agama-live; fi
 	$(MAKE) all
 	(cd $(DESTDIR) && osc build -M $(FLAVOR) images)
+
+.PHONY: build all clean