Makefile: remove more generated files on clean

make clean missed the source qmp files generated
by python. Fix that.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Makefile

@@ -8,6 +8,7 @@ ifeq ($(TRACE_BACKEND),dtrace)
 GENERATED_HEADERS += trace-dtrace.h
 endif
 GENERATED_HEADERS += qmp-commands.h qapi-types.h qapi-visit.h
+GENERATED_SOURCES += qmp-marshal.c qapi-types.c qapi-visit.c
 
 ifneq ($(wildcard config-host.mak),)
 # Put the all: rule here so that config-host.mak can contain dependencies.
@@ -227,6 +228,7 @@ clean:
 	rm -f trace.c trace.h trace.c-timestamp trace.h-timestamp
 	rm -f trace-dtrace.dtrace trace-dtrace.dtrace-timestamp
 	rm -f trace-dtrace.h trace-dtrace.h-timestamp
+	rm -f $(GENERATED_SOURCES)
 	rm -rf $(qapi-dir)
 	$(MAKE) -C tests clean
 	for d in $(ALL_SUBDIRS) $(QEMULIBS) libcacard; do \