string/test-memcpy error reporting

string/test-memcpy error reporting
http://sourceware.org/ml/libc-alpha/2013-08/msg00094.html

Using plain %s here runs the risk of segfaulting when displaying the
string.  src and dst aren't zero terminated strings.

	* string/test-memcpy.c (do_one_test): When reporting errors, print
	string address and don't overrun end of string.