Log Message:
Update to 1.6.1beta05 for a bugfix needed by wm/awesome (via
ImageMagick).

Version 1.6.1beta01 [February 16, 2013]
  Made symbol prefixing work with the ARM neon optimizations. Also allow
    pngpriv.h to be included for preprocessor definitions only, so it can
    be used in non-C/C++ files. Back ported from libpng 1.7.
  Made sRGB check numbers consistent.
  Ported libpng 1.5 options.awk/dfn file handling to 1.6, fixed one bug.
  Removed cc -E workround, corrected png_get_palette_max API Tested on
    SUN OS cc 5.9, which demonstrates the tokenization problem previously
    avoided by using /lib/cpp.  Since all .dfn output is now protected in
    double quotes unless it is to be macro substituted the fix should
    work everywhere.
  Enabled parallel tests - back ported from libpng-1.7.
  scripts/pnglibconf.dfa formatting improvements back ported from libpng17.
  Fixed a race condition in the creation of the build 'scripts' directory
    while building with a parallel make.
  Use approved/supported Android method to check for NEON, use Linux/POSIX
    1003.1 API to check /proc/self/auxv avoiding buffer allocation and other
    library calls (ported from libpng15).

Version 1.6.1beta02 [February 19, 2013]
  Use parentheses more consistently in "#if defined(MACRO)" tests.
  Folded long lines.
  Reenabled code to allow zero length PLTE chunks for MNG.

Version 1.6.1beta03 [February 22, 2013]
  Fixed ALIGNED_MEMORY support.
  Allow run-time ARM NEON checking to be disabled. A new configure option:
    --enable-arm-neon=always will stop the run-time checks. New checks
    within arm/arm_init.c will cause the code not to be compiled unless
    __ARM_NEON__ is set. This should make it fail safe (if someone asks
    for it on then the build will fail if it can't be done.)
  Updated the INSTALL document.

Version 1.6.1beta04 [February 27, 2013]
  Revised INSTALL to recommend using CPPFLAGS instead of INCLUDES.
  Revised scripts/makefile.freebsd to respect ZLIBLIB and ZLIBINC.
  Revised scripts/dfn.awk to work with the buggy MSYS awk that has trouble
    with CRLF line endings.

Version 1.6.1beta05 [March 2, 2013]
  Avoid a possible memory leak in contrib/gregbook/readpng.c
  Fixed bug introduced in libpng-1.6.0beta28 that causes libpng to handle chunks
    even when they have been tagged PNG_HANDLE_CHUNK_NEVER.