[RFT/RFA] Per-directory libjava builds (take 3)

[Paolo Bonzini]

> I still don't understand why you'd have the filelist depend on the
> source files at all.  Seems to me the filelist should depend only
> on the makefile.  The .class files and .lo files should depend on
> the source files and the filelist.
> 
> What do we gain by recreating the filelist after a source file changes?

It allows me to express the dependency of the .stamp file on the .list 
file, and to use a static pattern rule as in:

$(all_java_stamp_files): %.stamp: %.list


>>+%.list:
>>+	@: $(shell $(mkinstalldirs) $(basename $@))
>>+	@: $(call write_entries_to_file,$?,$@)
> 
> 
> This creates a list of only those files that have changed.  You want $^.

Actually I wanted $? because it could be ok for building the class 
files; but it is not for the .lo file, and these take much longer to 
rebuild than the class files -- so it would not saved a lot anyway. 
I've changed it to $^.

Paolo