Update Zlib to version 1.2.8

merge the latest open source zlib into chromium external projects

 Version 1.2.8 fixes a very rare bug in decompression. All users are encouraged to upgrade immediately. Version 1.2.8 also has these improvements:
    - Add new inflateGetDictionary() function
    - Fix bug where gzopen() immediately followed by gzclose() would write an empty file instead of an empty gzip stream.
    - Fix bug in gzclose() when gzwrite() runs out of memory
    Version 1.2.7 has many portability improvements over 1.2.6, and has these enhancements:
    - Fix bug in gzclose_w() when gzwrite() fails to allocate memory
    - Add "x" (O_EXCL) and "e" (O_CLOEXEC) modes support to gzopen()
    - Add gzopen_w() in Windows for wide character path names
    - Fix type mismatch between get_crc_table() and crc_table
    Version 1.2.6 has many changes over 1.2.5, including these improvements:
    - gzread() can now read a file that is being written concurrently
    - gzgetc() is now a macro for increased speed
    - Added a 'T' option to gzopen() for transparent writing (no compression)
    - Added deflatePending() to return the amount of pending output
    - Allow deflateSetDictionary() and inflateSetDictionary() at any time in raw mode
    - deflatePrime() can now insert bits in the middle of the stream
    - ./configure now creates a configure.log file with all of the results
    - Added a ./configure --solo option to compile zlib with no dependency on any libraries
    - Fixed a problem with large file support macros
    - Fixed a bug in contrib/puff
    - Many portability improvements

BUG=610615
R=agl@chromium.org
R=gavinp@chromium.org

Review-Url: https://codereview.chromium.org/1955383002
Cr-Original-Commit-Position: refs/heads/master@{#400647}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: a50849ae9ba1b2fad47905db521463b3bf085883