fix - 'asciiz/1' function of 'emysql_auth' module was fixed

[Shpaky]

'asciiz/1' function of 'emysql_auth' module was fixed.

Emysql/src/emysql_auth.erl

Line 91 in c7e2103

{Salt2, <<>>} = asciiz(Salt2_0),

here <<>> expects as second returning value, but it will be never received since binary:split/2 function doesn`t complement returning value.

Example:

1> binary:split(<<1,2,3,4,5,6,7,8,9,10,11,12,13>>,<<0>>).
[<<1,2,3,4,5,6,7,8,9,10,11,12,13>>]