Fix off-by-one error in ByteVector::find.

In case where the pattern has the same length as the bytevector, it should
degrade to A == B, not just return "not found" (e.g. A.find(A) should
return 0, not -1).


git-svn-id: svn://anonsvn.kde.org/home/kde/trunk/kdesupport/taglib@735107 283d02a7-25f6-0310-bc7c-ecb5cbfe19da