Install sqlite3 and libsqlite3-0 from mozilla.debian.net.

Otherwise, ISO builds fails since a hook of ours tries to get the former in its
newest version (from mozilla.d.n) and we have pinning that gets the later from
official backports, which are not compatible with each other.

config/chroot_apt/preferences

@@ -96,7 +96,7 @@ Pin: origin backports.debian.org
 Pin-Priority: 999
 
 Package: libsqlite3-0
-Pin: origin backports.debian.org
+Pin: origin mozilla.debian.net
 Pin-Priority: 999
 
 Package: libsys-statistics-linux-perl
@@ -299,6 +299,10 @@ Package: spice-vdagent
 Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
+Package: sqlite3
+Pin: origin mozilla.debian.net
+Pin-Priority: 999
+
 Package: tor
 Pin: origin deb.torproject.org
 Pin-Priority: 999