qpkg: converted dumb binary trees to red-black trees (in progress)

This is a change of the underlying mechanism but it's not polished or
optimized yet. The compare functions haven't been updated, so they work
but produce compiler warnings because of type mismatches.

- Makefile (OBJS): added jrb.o
- id.h, id.c: use jrb instead of own dumb binary trees
- TODO: brag about the efficiency improvement

qpkg/Makefile

@@ -2,7 +2,7 @@ CFLAGS = -Wall -Wshadow -Wmissing-prototypes -g -O
 # -O, so that we get data flow analysis, which helps to find more bugs
 #LDFLAGS=-pg
 
-OBJS = gobble.o id.o prereq.o qpkg.o
+OBJS = gobble.o id.o prereq.o qpkg.o jrb.o
 OBJS_rbtest = rbtest.o jrb.o
 
 all:	qpkg rbtest