bc: sync with OpenBSD
tty.c Rev. 1.3
Avoid unintended problems with operator precedence when doing an
assignment and comparison.
bc.1, Rev. 1.31, 1.32
'.Ql Quit' -> '.Ql quit' because only the lowercase command is valid.
Clarify sentence about `quit` in BUGS section.
extern.h, Rev. 1.12
whitespace
bc.y, Rev. 1.47
Prefer setvbuf() to setlinebuf() for portability
Obtained from: OpenBSD
c41fd18fc0