components/*.c: include slstatus.h

this gives the compiler a chance to check weather the prototype and
definiton matches or not, which would catch issues like 3c47701.

Makefile

@@ -31,7 +31,7 @@ COM =\
 
 all: slstatus
 
-$(COM:=.o): config.mk $(REQ:=.h)
+$(COM:=.o): config.mk $(REQ:=.h) slstatus.h
 slstatus.o: slstatus.c slstatus.h arg.h config.h config.mk $(REQ:=.h)
 
 .c.o: