tools/libfsimage: Fix clean and distclean make targets

If there is a single colon for a given target and the target
is redefined in another place (e.g. in included file) then
make executes only new target and displays following warning:

Makefile:35: warning: overriding commands for target `clean'
tools/libfsimage/common/../../../tools/libfsimage/Rules.mk:25:
warning: ignoring old commands for target `clean'

To cope with that issue define all required targets as double-colon
rules. Additionally, remove some redundant stuff.

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

tools/libfsimage/Rules.mk

@@ -21,7 +21,7 @@ fs-install: fs-all
 $(FSLIB): $(PIC_OBJS)
 	$(CC) $(LDFLAGS) $(SHLIB_LDFLAGS) -o $@ $^ -lfsimage $(FS_LIBDEPS) $(APPEND_LDFLAGS)
 
-clean distclean:
+clean distclean::
 	rm -f $(PIC_OBJS) $(FSLIB) $(DEPS)
 
 -include $(DEPS)

tools/libfsimage/common/Makefile

@@ -31,8 +31,8 @@ install: all
 	$(INSTALL_DATA) fsimage_plugin.h $(DESTDIR)$(INCLUDEDIR)
 	$(INSTALL_DATA) fsimage_grub.h $(DESTDIR)$(INCLUDEDIR)
 
-clean distclean:
-	rm -f $(PIC_OBJS) $(LIB) $(DEPS)
+clean distclean::
+	rm -f $(LIB)
 
 libfsimage.so: libfsimage.so.$(MAJOR)
 	ln -sf $< $@