Log Message:
Version 1.8.8 (built with libpng-1.6.26beta06 and zlib-1.2.8.1)
  Fixed "nolib" build (bug report by Hanspeter Niederstrasser).
    Make sure we use system-png.h, and not the local file.  It is now
    possible to build either the regular pngcrush or the "nolib"
    pngcrush in the complete pngcrush source directory (use
    "make clean" before rebuilding!)
  Fixed timing when using "clock()". Sometimes an additional second
    was added when the timer crossed a one-second boundary, since
    version 1.8.5.
  Upgrade libpng to version 1.6.26beta06 and zlib to 1.2.8.1.
  Use zlib-1.2.8.1 new "inflateValidate()" function to avoid checking
    ADLER32 checksums. Version 1.8.7 did not work when the "-fix"
    option was used.