Use "|" instead of "+" when combine the _IO_LINE_BUF and _IO_UNBUFFERED flags

Both of "_IO_UNBUFFERED" and "_IO_LINE_BUF"  are the bit flags, but I
find there are some codes looks like "_IO_LINE_BUF+_IO_UNBUFFERED",
while some codes are "_IO_LINE_BUF|_IO_UNBUFFERED".

I think the former is not good, even though the final result is same.