from upstream commit d3c3fb6e18a6b359c263156f556a5520121ca7fd

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.

diff --git a/GNUmakefile b/GNUmakefile
index a27b453..11bc3a1 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -261,7 +261,7 @@ beep-usage.c: beep-usage.txt
 define LINK_RULE
 $(1): $$($(2)_OBJS)
 	@: echo "LINK_RULE $$@: $$^"
-	$(CC) -Wl,-Map=$$(@:%=%.map),--cref $(CFLAGS) $(common_CFLAGS) $(LDFLAGS) $(common_LDFLAGS) -o $$@ $$^ $$($(2)_LIBS) $(common_LIBS) $(LIBS)
+	$(CC) -Wl,-Map=$$(@:%=%.map) $(CFLAGS) $(common_CFLAGS) $(LDFLAGS) $(common_LDFLAGS) -o $$@ $$^ $$($(2)_LIBS) $(common_LIBS) $(LIBS)
 
 $$(patsubst %.o,.deps/%.o.dep,$$($(2)_OBJS))):