on any access

Archive engine for 5.1 (and latter) version uses a modified 
version of zlib (azlib). These two version are incompatible
so a proper upgrade is needed before tables created in 5.0 
can be used reliable.

This upgrade can be performed using repair. But due to lack 
of test its risky to allow upgrade for now. This patch addresses
only the crashing issue. Any attempt to repair will be blocked.

Eventually repair can be allowed to run through (which will also
cause an upgrade from older version to newer) but only after a 
thorough testing.

mysql-test/r/archive.result:
  Updated result file for test case for bug#47012
mysql-test/std_data/bug47012.ARM:
  part of archive table (t1) created in mysql 5.0
mysql-test/std_data/bug47012.ARZ:
  part of archive table (t1) created in mysql 5.0
mysql-test/std_data/bug47012.frm:
  part of archive table (t1) created in mysql 5.0
mysql-test/t/archive.test:
  Added test case for bug#47012.
storage/archive/azio.c:
  Fixed a minor issues (minor version overwriting version in 
  stream structure)
  Removed assertion when an older version is found. Instead
  setting the correct version (2) in s->version
  If an unknown version is found marked it as corrupt.
storage/archive/ha_archive.cc:
  Detecting the archive version in getShare and marking
  it as need to upgrade.
  Blocking open if the archive needs an upgrade. This
  can be allowed in case of open for repair to upgrade
  the archive but needs to tested.