some changes to Makefiles and added top-level Makefile

Makefile

@@ -0,0 +1,7 @@
+all:
+	make -C buildutils all
+	make -C src all
+
+clean:
+	make -C buildutils clean
+	make -C src clean

buildutils/Makefile

@@ -1,4 +1,4 @@
-ALL: mksplash
+all: mksplash
 
 mksplash: mksplash.c
 	gcc -o mksplash -O -Wall -I/usr/include/libpng mksplash.c -lpng16 -lz

src/Makefile

@@ -2,6 +2,8 @@ OBJS=main.o sysinput.o fbinit.o fbprimitive.o log.o gpio.o msg_queue.o time_func
 LIBS=-lbcm2835 -lpthread
 CFLAGS=-g -O -DDEBUG_ASSERT
 
+all: upiwin
+
 upiwin: $(OBJS)
 	gcc -o upiwin $(OBJS) $(LIBS)