Description:
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When insert some japanese charectar (encoding type is "SJIS") using OCIBindByName and oci_execute, oracle has return the ORA-12899 error,it is seems like some addition bytes has been added after OCIBindByName.

Reproduce code:
---------------
//a table with 2 column, 
//empno -- number(1)
//ename -- varchar2(6)
$stmt = oci_parse($conn, " INSERT INTO                                    emp (empno, ename)  VALUES( :0, :1)");

$ret = OCIBindByName(stmt, ':0', 1);
//error check
...
$ret = OCIBindByName(stmt, ':1', '日本語');
//error check
...

$ret = oci_execute($stmt);

//error check
...


oracle's error shows :
ORA-12899: value too large for column "USER0"."MyTable"."ename" (actual: 9, maximum: 6)]

Expected result:
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The string: '日本語' should be 6 bytes, 
echo strlen('日本語'); //should show us : 6