evalbytes should ignore outer utf8 declaration

evalbytes should ignore outer utf8 declaration

A slight mistake in the evalbytes.t test script caused a lot of tests
not be testing what they were supposed to be testing for.  I used
'qq(\x...)' instead of qq('\x...').  (I.e., I was trying to embed lit-
eral Unicode characters in the string, rather than pass escapes to
evalbytes.)

I had wondered at the time why it worked without my doing anything, so
I probably should have looked deeper.