bzr push into mysql-5.6 branch (chaithra.gopalareddy:4048 to 4049)

[Chaithra Gopalareddy]

 4049 Chaithra Gopalareddy	2012-07-19 [merge]
      Null merge from 5.5 to 5.6

 4048 Satya Bodapati	2012-07-18
      BUG#14212892 - WHY DOES BUF_PAGE_GET_GEN CONFIRM THE PAGE
                     CHECKSUM FOR COMPRESSED PAGES
      
      For compressed pages, page checksum verification is done
      when reading the page from disk and also while decompressing
      the compressed pages.
      
      Since page checksum verification is already done when
      the page is read from disk, it is not necessary to verify the
      checksums again when decompressing the page. By removing the extra
      page checksum verification, the CPU used will be saved.
      
      No mtr testcase as this change is covered by existing testcases.
      
      Approved by Inaam: rb://1166
     @ storage/innobase/buf/buf0buf.cc
        call buf_zip_decompress() with FALSE in buf_page_get_gen() to
        disable page checksum verification when reading the page from
        disk

    modified:
      storage/innobase/buf/buf0buf.cc
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