best make to rebuild libgcj?

[Heitzso]

I need to debug/trace through some classpath code.

Whether I add debugging to that lib (and my code) and use an
official debugger, or just slip in some "System.out.println()"s
for some old fashioned debugging, I need to rebuild the
gcj classpath library.

Where in my 4.1 snapshot obj tree should I invoke what "make"
command to efficiently rebuild libgcj.so w/o starting from
scratch w/ "make bootstrap" and waiting a couple hours?

Thanks,
Heitzso