Avoid --cref linker option

Not all linkers support that option, and it seems the option was included
solely for informational purposes (possibly to debug issues in the past).
Therefore, it appears safe to remove the option from the makefile.

GNUmakefile

@@ -319,7 +319,7 @@ $(2)_OBJS := $$(foreach src,$$($(2)_SOURCES),$$(if $$(filter %.c,$$(src)),$$(src
 $(1): $$($(2)_OBJS)
 	$$(inhibit-build-command)
 	@$$(call print-rule-description,LINK,$$@)
-	$$(CC) -Wl,-Map=$(1).map,--cref $$(common_CFLAGS) $$(CFLAGS) $$(common_LDFLAGS) $$($(2)_LDFLAGS) $$(LDFLAGS) -o $$@ $$^ $$(common_LDADD) $$($(2)_LDADD) $$(LDADD)
+	$$(CC) -Wl,-Map=$(1).map $$(common_CFLAGS) $$(CFLAGS) $$(common_LDFLAGS) $$($(2)_LDFLAGS) $$(LDFLAGS) -o $$@ $$^ $$(common_LDADD) $$($(2)_LDADD) $$(LDADD)
 
 $$(patsubst %.o,.deps/%.o.dep,$$($(2)_OBJS))):