scripts/dpkg-buildpackage.sh: we know that dpkg-architecture is

scripts/dpkg-buildpackage.sh: we know that dpkg-architecture is
installed since we provide it, so don't test for its existance
More updates from Marcus Brinkman:
+ archtable: Change first column format from CPU to CPU-OS.
  Add entry for i386-gnu. Update comment.
+ configure.in: Check Debian architecture revamped:
  More appropriate check title. Check for CPU-OS in arhctable (instead
  just CPU). Enclose result message in [...] (because of the comma
  character). After the test, $dpkg_archset can't be empty, so remove
  following test which is always true.
+ Remove internal use of --print-architecture:
  scripts/controllib.pl: Use always dpkg-architecture -qDEB_HOST_ARCH
  scripts/dpkg-buildpackage: Don't set $arch at command line parsing time,
    instead, always set it later with dpkg-architecture -qDEB_HOST_ARCH
  dpkg-name.pl: Fall back to dpkg --print-installation-architecture.