[PATCH] Fix string/test-strncmp.c to work with wide chars.

[Jose E. Marchesi]

    > wcsmbs/test-wcsncmp.c (i.e. string/test-strncmp with defined WIDE)
    > triggers a signal in aligment-strict platforms, like sparc*-*-*.
    > 
    > This patch fixes string/test-strncmp.c to work properly when the test is
    > performed on arrays of wide chars.  This includes passing align1 and
    > align2 to do_test as bytes, and to use more meaningful values for middle
    > chars and large chars.
    
    A different patch (about which Carlos had some concerns) was posted at 
    <https://sourceware.org/ml/libc-alpha/2015-07/msg00698.html>.  How do the 
    two compare?

Oh, I missed that patch from davem.

In the patch I am taking the same approach than in string/test-strcmp.c
and other existing tests, i.e. to keep do_test and do_test_final
interpreting align1 and align2 in number of characters, and not bytes.
The character->bytes conversion is performed by the caller.

It also adapts the middle-char and high-char values used in the tests to
wide chars, i.e. 255 is not a high value in the range of wide chars.

Note that dave's approach is used in some other tests, like
string/test-memcmp.c.

Both approaches are equally valid IMO.