AR was called with "u" which causes objects of same name not to be updated,
thus resulting in random files present in it for duplicate names depending on
build order. It happens that "addr.o" and "family.o" exist in two directories
and would replace each other. However in order to deduplicate the entry, it
is necessary to store the full path using "P". An alternative could be to
rename conflicting files.

--- ./lib/Makefile.orig	2019-12-02 16:26:12.784991745 +0100
+++ ./lib/Makefile	2019-12-02 16:26:24.696983150 +0100
@@ -58,7 +58,7 @@
 
 $(OUT_AR):  ../Makefile.opts $(OBJ)
 	@echo "  AR $(OUT_AR)";
-	$(AR) crus $(OUT_AR) $(OBJ)
+	$(AR) crP $(OUT_AR) $(OBJ)
 
 clean:
 	@echo "  CLEAN lib";