segfault in test-strcmp

[Roland McGrath]

I looked at the test-strchr crash before the test-strcmp one, but I suspect
the problem is similar.  The sysdeps/powerpc/powerpc32/strchr.S code is
accessing the word following the word containing the search character.
This faults because the test string is aligned on the end of a page so that
the following word cannot be accessed (this happens on iteration 157 in
test-strchr with no srandom).  The test program is arguably invoking
undefined behavior, because the string is actually not terminated: the
final word of the page contains the search character and three other
nonzero bytes.  So a stupid but valid implementation of strchr that called
strlen would crash.

It may be quicker for someone who knows powerpc assembly better than I do
to try to fix this.