This test fails with the following error on AArch64 with -Xcomp or
tiered compilation:

  Buffer overrun: ISO-8859-1 "\u8a8e"[0/1] => UNMAPPABLE[1] ""[0/19] -114
  failures=1

  Passed = 223410156, failed = 10000

  STDERR:
  java.lang.AssertionError: Some tests failed
          at FindEncoderBugs.main(FindEncoderBugs.java:526)

The problem is caused by the encoder function for the ISO-8859-1
character set writing one extra character to the output array when it
encounters a character it can't encode.

This is implemented as an intrinisc on AArch64. But the intrinisic
doesn't excatly match the original Java code in ISO_8859_1.java:

  @HotSpotIntrinsicCandidate
  private static int implEncodeISOArray(char[] sa, int sp,
                                        byte[] da, int dp, int len) {
      int i = 0;
      for (; i < len; i++) {
          char c = sa[sp++];
          if (c > '\u00FF') // (1)
              break;
          da[dp++] = (byte)c; // (2)
      }
      return i;
  }

In the intrinsic code statements (1) and (2) are swapped.