build: Add .config file to dependencies

If the .config file changes, basically everything needs to be
rebuilt since we don't try to detect which symbols changed or
such. Now that the .config file handling is in the common
build system, make everything depend on it if there's one.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

src/build.rules

@@ -76,10 +76,10 @@ _DIRS := $(BUILDDIR)/$(PROJ)
 _make_dirs:
 	@mkdir -p $(_DIRS)
 
-$(BUILDDIR)/$(PROJ)/src/%.o: $(ROOTDIR)src/%.c | _make_dirs
+$(BUILDDIR)/$(PROJ)/src/%.o: $(ROOTDIR)src/%.c $(CONFIG_FILE) | _make_dirs
 	$(Q)$(CC) -c -o $@ $(CFLAGS) $<
 	@$(E) "  CC " $<
-$(BUILDDIR)/$(PROJ)/%.o: %.c | _make_dirs
+$(BUILDDIR)/$(PROJ)/%.o: %.c $(CONFIG_FILE) | _make_dirs
 	$(Q)$(CC) -c -o $@ $(CFLAGS) $<
 	@$(E) "  CC " $<
 

wpa_supplicant/Makefile

@@ -1866,8 +1866,6 @@ wpa_priv: $(BCHECK) $(OBJS_priv)
 	$(Q)$(LDO) $(LDFLAGS) -o wpa_priv $(OBJS_priv) $(LIBS)
 	@$(E) "  LD " $@
 
-$(OBJS_c) $(OBJS_t) $(OBJS_t2) $(OBJS) $(BCHECK) $(EXTRA_progs): .config
-
 _OBJS_VAR := OBJS
 include ../src/objs.mk
 wpa_supplicant: $(BCHECK) $(OBJS) $(EXTRA_progs)