Makefile: be a little more conventional

The all target will build the programs, and each program has its
source as build dep.

Signed-off-by: Serge Hallyn <shallyn@cisco.com>

Makefile

@@ -2,28 +2,32 @@ PREFIX:=/
 
 .PHONY: install shellcheck
 
+PROGRAMS = programs/sxmo_setpineled programs/sxmo_setpinebacklight programs/sxmo_screenlock programs/sxmo_megiaudioroute programs/sxmo_megiaudioroute
+
+all: shellcheck $(PROGRAMS)
+
 shellcheck:
 	shellcheck scripts/*/*
 
-programs/sxmo_setpineled:
+programs/sxmo_setpineled: programs/sxmo_setpineled.c
 	gcc -o programs/sxmo_setpineled programs/sxmo_setpineled.c
 
-programs/sxmo_setpinebacklight:
+programs/sxmo_setpinebacklight: programs/sxmo_setpinebacklight.c
 	gcc -o programs/sxmo_setpinebacklight programs/sxmo_setpinebacklight.c
 
-programs/sxmo_screenlock:
+programs/sxmo_screenlock: programs/sxmo_screenlock.c
 	gcc -o programs/sxmo_screenlock programs/sxmo_screenlock.c -lX11
 
-programs/sxmo_megiaudioroute:
+programs/sxmo_megiaudioroute: programs/sxmo_megiaudioroute.c
 	gcc -o programs/sxmo_megiaudioroute programs/sxmo_megiaudioroute.c
 
-programs/sxmo_vibratepine:
+programs/sxmo_vibratepine: programs/sxmo_vibratepine.c
 	gcc -o programs/sxmo_vibratepine programs/sxmo_vibratepine.c
 
 clean:
 	rm programs/sxmo_setpineled programs/sxmo_screenlock programs/sxmo_setpinebacklight programs/sxmo_megiaudioroute programs/sxmo_vibratepine
 
-install: programs/sxmo_setpineled programs/sxmo_setpinebacklight programs/sxmo_screenlock programs/sxmo_megiaudioroute programs/sxmo_vibratepine
+install: $(PROGRAMS)
 	mkdir -p $(PREFIX)/usr/share/sxmo
 	cp -r configs/* $(PREFIX)/usr/share/sxmo