Makefile: Avoid explicit list of directories in clean target

Avoid having an explicit list of directories in the 'clean'
target by using 'find' to remove all .o and .d files instead.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Makefile

@@ -214,13 +214,10 @@ clean:
 # avoid old build problems by removing potentially incorrect old files
 	rm -f config.mak op-i386.h opc-i386.h gen-op-i386.h op-arm.h opc-arm.h gen-op-arm.h
 	rm -f qemu-options.def
-	rm -f *.o *.d *.a *.lo $(TOOLS) $(HELPERS-y) qemu-ga TAGS cscope.* *.pod *~ */*~
+	find . -name '*.[od]' -exec rm -f {} +
+	rm -f *.a *.lo $(TOOLS) $(HELPERS-y) qemu-ga TAGS cscope.* *.pod *~ */*~
 	rm -Rf .libs
-	rm -f slirp/*.o slirp/*.d audio/*.o audio/*.d block/*.o block/*.d net/*.o net/*.d fsdev/*.o fsdev/*.d ui/*.o ui/*.d qapi/*.o qapi/*.d qga/*.o qga/*.d
-	rm -f qom/*.o qom/*.d libuser/qom/*.o libuser/qom/*.d
-	rm -f hw/usb/*.o hw/usb/*.d hw/*.o hw/*.d
 	rm -f qemu-img-cmds.h
-	rm -f trace/*.o trace/*.d
 	rm -f trace-dtrace.dtrace trace-dtrace.dtrace-timestamp
 	@# May not be present in GENERATED_HEADERS
 	rm -f trace-dtrace.h trace-dtrace.h-timestamp