BUILD: makefile: build halog with the correct flags

halog currently emits lots of warnings because it does not benefit from
the default flags. Let's update the main makefile to build it by itself
and remove the other one. The sub-project's makefile was replaced with
A readme indicating how to build it.
diff --git a/Makefile b/Makefile
index 29d75fe..327dbc1 100644
--- a/Makefile
+++ b/Makefile
@@ -926,8 +926,8 @@
 %.o:	%.c $(DEP)
 	$(cmd_CC) $(COPTS) -c -o $@ $<
 
-admin/halog/halog:
-	$(Q)$(MAKE) -C admin/halog halog CC='$(cmd_CC)' OPTIMIZE='$(COPTS)'
+admin/halog/halog: admin/halog/halog.o admin/halog/fgets2.o src/ebtree.o src/eb32tree.o src/eb64tree.o src/ebmbtree.o src/ebsttree.o src/ebistree.o src/ebimtree.o
+	$(cmd_LD) $(LDFLAGS) -o $@ $^ $(LDOPTS)
 
 dev/flags/flags: dev/flags/flags.o
 	$(cmd_LD) $(LDFLAGS) -o $@ $^ $(LDOPTS)