Bug 6042

Some vague efforts have been made to get dbus to build with
builddir != srcdir, but they haven't been taken very far (e.g.,
not as far as actually working).  There is also a lot of
gunge supplying ABSOLUTE_TOP_BUILDDIR to the tests.
(a) This is unnecessary; @abs_top_builddir@ already exists
(b) This is wrong: several should be @abs_top_srcdir@

gcj/org/freedesktop/dbus/Makefile.am tries to get it right and fails:
unwisely trying to imitate something from the autotools, it plays
with -I$(srcdir)/$(top_builddir), but it's in the wrong place, and
the result is merely a broken ooncatenation of paths.

Following an almost universal convention, nobody has bothered
making Doxyfile work properly in this case.  Weirdly, there
already is a Doxyfile.in, used for other configuration
purposes, but the (easy-as-falling-off-a-log) changes to
handle a separate build directory have not been made.

Here are two patches.
(a) Patches for CVS (the Real Thing)
(b) A patch for the *RELEASE* (since I was working from the 0.60 release)
which does the corresponding magic with configure
and <various>/Makefile.in files.

*** IMPORTANT NOTE ***
Some built files are lying around in the release, for no very good reason.
This is obviously pointless: in fact, it's wicked as well, because
it breaks building in a separate build directory.  One can't invoke
'make clean' to get rid of them, because the release doesn't have the
Makefiles, but one can't leave them there either.  One may even end up
(re-)building the file because the Make rules specify that it ought to be
re-built, but the old one will still be used!  The default rules for
GNU make will always pick up an object from the source tree in preference
to something (even more recent) in the build tree.  

The offending files are:
test/data/valid-config-files/debug-allow-all.conf
test/data/valid-config-files/debug-allow-all-sha1.conf
test/data/valid-service-files/debug-echo.service
test/data/valid-service-files/debug-glib.service
test/data/valid-service-files/debug-python.service
test/data/valid-service-files/debug-segfault.service
test/data/valid-service-files/debug-shell-echo-fail.service
test/data/valid-service-files/debug-shell-echo-success.service

*** IMPORTANT NOTE 2 ***
The build process seems to use installed headers in preference to the
local headers, if it finds them in the usual INCLUDE search-path.
I haven't exerted myself to make this work differently, but it
is certainly doable (gcc, at least, allows the usual search-path
for #include <xxx.h>-type headers to be rewritten).  This has got
to be good for developers who may modify the headers!