files (for the same package and version) before generating the new ones.
Similarly change "make install-deb" and "make upload-dist" so that
they are more selective in which files they install.

This fixes a bug where "make install-deb" tried to install the wrong
.deb files, because it just did "rpm -i *.deb", and there can be old
.deb files lying around.  It also fixes a similar problem in "make
upload-dist".

Also, add a "tags" target to the Makefile.

Reviewers: Craig Silverstein

dist' makes a tar.gz file), and 'make deb' to make the deb files.
'make alldist' will make all three (well, four): .tar.gz, .tar.bz2,
.rpm, and .deb.

The rpm.spec file that's used is based on the old distcc.spec file,
which is now deleted.  However, it's reordered to look a bit more like
other spec files for Google projects, removes the obsolete
'include-server' package (that's now part of the distcc package
proper), and takes out all the ChangeLog entries that don't relate to
the spec file in particular.

I also added a script, rpm.sh, to build the rpm file, which is a
combination of the rpm.sh script used to build other google projects,
and the existing build-distcc.sh, which is now deleted.  Mostly it
just calls rpmbuild with the right flags.  deb.sh could have re-done
all the work that rpm.spec and rpm.sh does, but instead we just use
"alien" to convert the rpm to a deb file.

Tested by installing the deb files (both client and server) on my home
machine and then running 'make maintainer-installcheck'.

Reviewed by fergus@google.com