Update to 1.6923

Upstream changes:
1.6923  2013-07-03 22:16:04 PDT
  [Bug Fixes]
      - Reverted the --skipdeps in PERL_AUTOINSTALL since it breaks default
        dependencies in Module::Install-based distributions

1.6922  2013-06-19 13:55:54 PDT
  [Improvements]
      - No changes in the code, packaging update so the fatpacked executable on cpanm has
        the right version. #274

1.6921  2013-06-18 03:18:55 PDT
  [Bug Fixes]
      - Fixes install with Module::Build < 0.35, i.e. vanilla perl 5.10.1
        (Thanks to joshk for the report)
      - Fixes install on 5.8 with Module::Build dists without configure_requires #273
        (Thanks to gildegoma for the report)

1.6920  2013-06-14 14:08:44 PDT
  [Improvements]
      - Handle PERL_LOCAL_LIB_ROOT in case multiple paths are stacked (mst)
      - Remove the search.cpan.org fallback where no META files exist. Generate stub using CPAN::Meta

1.6919  2013-06-12 08:32:06 PDT
  [Incompatible Changes]
      - Automatically detect local::lib mode when environment variables are already configured
        on the shell. This is to fix the first time run when local::lib is configure but arch
        library path doesn't exist. #263

1.6918  2013-06-10 13:02:06 PDT
  [Improvements]
      - Fix documentation about --quiet
      - Find the best (non-backpan) match out of MetaCPAN results when there are multiple
        results https://github.com/CPAN-API/cpan-api/issues/274

1.6917  2013-06-05 10:07:12 JST
  [Incompatible Changes]
      - build.log is now created inside a work directory, then a symlink to the file is
        made in ~/.cpanm. On platforms where symlink is not available (Win32), the build.log
        file is copied from the build directory once the installation has finished. (ilmari)

1.6916  2013-06-04 19:54:36 JST
  [Improvements]
      - Do not complain upgrading cpanm in local::lib
      - Accept 0-9_ in PAUSE ID (#265)

(wen)