Bug 1805: Fixed 2 bugs in ICMP.computeChecksum().

  * Fixed a bug that caused ArrayIndexOutOfBoundsException if the size
    of the payload was odd.
  * Fixed a bug that generated incorrect checksum if the 16-bit checksum
    overflowed more than 255 times.

Change-Id: I8f26cc41dec2d5ba64c3ab31e66a846dfbea7bc5
Signed-off-by: Shigeru Yasuda <s-yasuda@da.jp.nec.com>
Merge "Bug 1805: Fixed 2 bugs in ICMP.computeChecksum()."