Pattern matching operations produces incorrect results when MULTIBYTE is not set

[guuu@xxxxxxxxxxx]

When MULTIBYTE support turned off, all the indexing and counting of pattern
matching operations becomes wrong.

    unsetopt MULTIBYTE; a=abcdef
(N) (length of matching fragment) returns length of source string despite of
fragment found or not:
    echo ${(N)a#abc} ${(N)a#qwe}
    6 6
(B) and (E) (beginning and end of matching fragment) returns length of source
string +1:
    echo ${(SB)a#b} ${(SE)a#b}
    7 7

Bug is confirmed on current git master version.