Makefile.am: move CLEANFILES= to top Makefile

It's easier to setup CLEANFILES to $(NULL) at the top makefile and then
always append to it whenever needed.

modules/Makefile.am

@@ -6,7 +6,7 @@ noinst_HEADERS =
 check_PROGRAMS =
 pkglibexec_PROGRAMS =
 EXTRA_DIST =
-
+CLEANFILES =
 
 SUBDIRS = .
 TESTS =

modules/common.am

@@ -10,7 +10,7 @@ AUTOMAKE_OPTIONS = subdir-objects
 NULL =
 pluginsdir = $(pkglibdir)/plugins
 BUILT_SOURCES =
-CLEANFILES = $(BUILT_SOURCES)
+CLEANFILES += $(BUILT_SOURCES)
 
 LTLIBVLCCORE = $(top_builddir)/src/libvlccore.la
 

modules/gui/qt/Makefile.am

@@ -11,6 +11,8 @@
 # For each qml and js resource
 #   - Add it to ..._QML
 
+CLEANFILES =
+
 include ../../common.am
 guidir = $(pluginsdir)/gui
 gui_LTLIBRARIES =