Clean up LDLIBS handling

We currently set LDLIBS to include libyaml globally if we're using it.
However only dtc itself actually needs to link with libyaml - the other
tool binaries don't.  Avoid that unnecessary inclusion by making LDLIBS
handling per-target.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Makefile

@@ -51,7 +51,7 @@ NO_YAML := $(shell $(PKG_CONFIG) --exists yaml-0.1; echo $$?)
 ifeq ($(NO_YAML),1)
 	CFLAGS += -DNO_YAML
 else
-	LDLIBS += $(shell $(PKG_CONFIG) --libs yaml-0.1)
+	LDLIBS_dtc += $(shell $(PKG_CONFIG) --libs yaml-0.1)
 endif
 
 ifeq ($(HOSTOS),darwin)
@@ -330,7 +330,7 @@ clean: libfdt_clean pylibfdt_clean tests_clean
 #
 %: %.o
 	@$(VECHO) LD $@
-	$(LINK.c) -o $@ $^ $(LDLIBS)
+	$(LINK.c) -o $@ $^ $(LDLIBS_$*)
 
 %.o: %.c
 	@$(VECHO) CC $@