* ext/zlib/zlib.c (rb_gzfile_set_mtime): Use NUM2UINT.
  The old logic doesn't work well on LP64 platforms as:
  .. -2**63-1 => error,
  -2**63 .. -2**62-1 => success,
  -2**62 .. -2**31-1 => error,
  -2**31 .. 2**31-1 => success,
  2**31 .. 2**62-1 => error,
  2**62 .. 2**64-1 => success,
  2**64 ..  => error.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40040 b2dd03c8-39d4-4d8f-98ff-823fe69b080e