reallocarray introduction available on glibc 2.26. allocates an array of m*n elements but checking for overflow.

those functions differently than the strn* ones as
they do not pad with zero to remaining bytes but guarantees
a null terminator.

BufWriter has more capacity (8k vs 1k) and doesn't flush the stream after '\n'.
That change helps to reduce the number of syscalls, especially when dealing with text files.

Since BufWriter has a different way of getting number of pending elements than LineWriter -
Pending trait was introduced to deal with that.

When a byte-oriented stream function touches a stream, that stream
should be set to byte-oriented mode if it hasn't been set yet. If
it has been set, the opertion should only succeed if the stream is
already in byte-oriented mode.

Signed-off-by: Wren Turkal <wt@penguintechs.org>

Signed-off-by: Wren Turkal <wt@penguintechs.org>

This function is used to set the orientation of a stream to either
byte-oriented or wchar-oriented.

More info on this function is here:
https://man7.org/linux/man-pages/man3/fwide.3p.html



This implementation only impmlemnts the manual switching and does
not yet guard against using a byte-oriented stream with wchar
functions and vice versa. Those step will come in additional
commits.

Signed-off-by: Wren Turkal <wt@penguintechs.org>

Oops, forgot to initiate the pointer after uses of CVec::new()