This makes the packaging easier to read and modify.
Features added:
* runs ‘make’ with the -j option for a tiny speedup
* uses appropriate compiler flags even when run directly instead of
through dpkg-buildpackage
* after interrupting a partial build, there is no need any more
for (fake) root privileges to clean up
* after interrupting a partial build, ‘debian/rules clean’ will
work without running autoreconf again.
Features retained:
* ‘debian/rules -n <target>’ provides the list of commands used
to make that target.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
