Merge pull request #253 from euanh/build-improvements

pbuilder: Remove avsm's deb-src, too
Merge pull request #254 from euanh/build-improvements

pbuilder: Fix typo in pbuilderrc
Only attempt to install packages if they are not present
Merge pull request #255 from BobBall/master

Only attempt to install packages if they are not present
Merge pull request #256 from euanh/build-improvements

mappkgname: Drop architecture annotations when mapping package names
configure: Install ocaml to work around spec files which build opt targets conditionally

makedeb.py expands the spec file %build recipe on the host,
not in a chroot.   The opt target in the %build recipe of some
spec files, such as ocaml-libvirt, is conditional on the existence
of %{_bindir}/ocamlopt.   If ocaml isn't installed on the host,
the opt target won't be included, even though ocamlopt is available
in the chroot.

Installing ocaml on the build host is a quick workaround;  the proper
fix is either to override the check for %{_bindir}/ocamlopt in the
spec file (harder than you might think to do this neatly) or to
run makedeb in the chroot (slow, but accurate).

Signed-off-by: Euan Harris <euan.harris@citrix.com>